Package Exports
- rambda
This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (rambda) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.
Readme
Rambda
Rambda is smaller and faster alternative to the popular functional programming library Ramda. - Documentation
Example use
import { compose, map, filter } from 'rambda'
const result = compose(
map(x => x * 2),
filter(x => x > 2)
)([1, 2, 3, 4])
// => [6, 8]You can test this example in Rambda's REPL
Rambda's advantages
- Typescript included
Typescript definitions are included in the library, in comparison to Ramda, where you need to additionally install @types/ramda.
Still, you need to be aware that functional programming features in Typescript are in development, which means that using R.compose/R.pipe can be problematic.
- Smaller size
The size of a library affects not only the build bundle size but also the dev bundle size and build time. This is important advantage, expecially for big projects.
- Tree-shaking
Currently Rambda is more tree-shakable than Ramda - proven in the following repo.
The repo holds two Angular9 applications: one with small example code of Ramda and the other - same code but with Rambda as import library.
Currently the Ramda bundle size is {{rambdaTreeShakingInfo}} MB less than its Ramda counterpart.
There is also Webpack/Rollup/Parcel/Esbuild tree-shaking example including several libraries including Ramda, Rambda and Rambdax.
actually tree-shaking is the initial reason for creation of
Rambda
- dot notation for
R.pathandR.paths
Standard usage of R.path is R.path(['a', 'b'], {a: {b: 1} }).
In Rambda you have the choice to use dot notation(which is arguably more readable):
R.path('a.b', {a: {b: 1} })- comma notation for
R.pickandR.omit
Similar to dot notation, but the separator is comma(,) instead of dot(.).
R.pick('a,b', {a: 1 , b: 2, c: 3} })
// No space allowed between properties- Speed
Rambda is generally more performant than Ramda as the benchmarks can prove that.
- Support
Most of the valid issues are fixed within 2-5 days.
Closing the issue is usually accompanied by publishing a new patch version of Rambda to NPM.
- More generic methods
Ramda has an overwhelming list of methods, as one could get lost putting all these methods in one's head. Rambda has smaller method counts and that could be seen as advantage.
Click to see the full list of 103 Ramda methods not implemented in Rambda
- __
- addIndex
- ap
- aperture
- apply
- applyTo
- ascend
- binary
- bind
- call
- comparator
- composeK
- composeP
- composeWith
- construct
- constructN
- contains
- countBy
- descend
- differenceWith
- dissocPath
- dropLastWhile
- dropRepeats
- dropRepeatsWith
- dropWhile
- empty
- eqBy
- eqProps
- evolve
- forEachObjIndexed
- gt
- gte
- hasIn
- innerJoin
- insert
- insertAll
- into
- invert
- invertObj
- invoker
- juxt
- keysIn
- lift
- liftN
- lt
- lte
- mapAccum
- mapAccumRight
- mapObjIndexed
- memoizeWith
- mergeDeepLeft
- mergeDeepWith
- mergeDeepWithKey
- mergeRight
- mergeWith
- mergeWithKey
- nAry
- nthArg
- o
- objOf
- once
- or
- otherwise
- pair
- partialRight
- pathSatisfies
- pickBy
- pipeK
- pipeP
- pipeWith
- project
- propSatisfies
- props
- reduceBy
- reduceRight
- reduceWhile
- reduced
- remove
- scan
- sequence
- sortWith
- splitAt
- splitWhen
- symmetricDifferenceWith
- takeLastWhile
- andThen
- toPairsIn
- transduce
- traverse
- unapply
- unary
- uncurryN
- unfold
- unionWith
- uniqBy
- unnest
- until
- useWith
- valuesIn
- xprod
- zipWith
- thunkify
- default
Install
yarn add rambda
For UMD usage either use
./dist/rambda.umd.jsor the following CDN link:
https://unpkg.com/rambda@CURRENT_VERSION/dist/rambda.umd.js- with deno
import {compose, add} from 'https://raw.githubusercontent.com/selfrefactor/rambda/master/dist/rambda.esm.js'Differences between Rambda and Ramda
Rambda's type detects async functions and unresolved
Promises. The returned values are'Async'and'Promise'.Rambda's type handles NaN input, in which case it returns
NaN.Rambda's path and paths accept dot notation -
'x.y' same as ['x','y']Rambda's pick and omit accept comma notation -
'x,y' same as ['x','y']Rambda's map, reject and forEach can iterate over objects not only arrays.
Rambda's map and filter pass array index as second argument when mapping over arrays.
Rambda's adjust, all, allPass, any, anyPass, findIndex , findLastIndex and reject are passing index as second argument to the predicate function.
Rambda's filter returns empty array with bad input(
nullorundefined), while Ramda throws.Ramda's includes will throw an error if input is neither
stringnorarray, while Rambda version will returnfalse.Ramda's clamp work for letters, while Rambda's method work only for numbers.
If you need more Ramda methods in Rambda, you may either submit a
PRor check the extended version of Rambda - Rambdax. In case of the former, you may want to consult with Rambda contribution guidelines.
Benchmarks
Click to expand all benchmark results
There are methods which are benchmarked only with Ramda and Rambda(i.e. no Lodash).
Note that some of these methods, are called with and without curring. This is done in order to give more detailed performance feedback.
The benchmarks results are produced from latest versions of Rambda, Lodash(4.17.19) and Ramda(0.27.0).
Ramda and Rambda(i.e. no Lodash).| method | Rambda | Ramda | Lodash |
|---|---|---|---|
| add | 96.25% slower | 96.24% slower | 🚀 Fastest |
| adjust | 🚀 Fastest | 5.52% slower | 🔳 |
| all | 🚀 Fastest | 94.95% slower | 🔳 |
| allPass | 🚀 Fastest | 98.95% slower | 🔳 |
| any | 🚀 Fastest | 98.18% slower | 6.18% slower |
| anyPass | 🚀 Fastest | 99.09% slower | 🔳 |
| append | 🚀 Fastest | 84.09% slower | 🔳 |
| applySpec | 🚀 Fastest | 75.73% slower | 🔳 |
| assoc | 87.98% slower | 57.39% slower | 🚀 Fastest |
| clone | 🚀 Fastest | 96.03% slower | 91.75% slower |
| compose | 🚀 Fastest | 96.45% slower | 77.83% slower |
| converge | 49.12% slower | 🚀 Fastest | 🔳 |
| curry | 🚀 Fastest | 34.9% slower | 🔳 |
| curryN | 63.32% slower | 🚀 Fastest | 🔳 |
| defaultTo | 🚀 Fastest | 50.3% slower | 🔳 |
| drop | 🚀 Fastest | 97.45% slower | 🔳 |
| dropLast | 🚀 Fastest | 97.07% slower | 🔳 |
| equals | 72.11% slower | 79.48% slower | 🚀 Fastest |
| filter | 🚀 Fastest | 94.74% slower | 58.18% slower |
| find | 🚀 Fastest | 98.2% slower | 88.96% slower |
| findIndex | 🚀 Fastest | 97.97% slower | 79.39% slower |
| flatten | 6.56% slower | 95.38% slower | 🚀 Fastest |
| ifElse | 🚀 Fastest | 70.97% slower | 🔳 |
| includes | 🚀 Fastest | 71.7% slower | 🔳 |
| indexOf | 🚀 Fastest | 84.08% slower | 7.86% slower |
| init | 94.42% slower | 97.55% slower | 🚀 Fastest |
| is | 🚀 Fastest | 11.72% slower | 🔳 |
| isEmpty | 51.68% slower | 93.82% slower | 🚀 Fastest |
| last | 🚀 Fastest | 99.64% slower | 1.05% slower |
| lastIndexOf | 🚀 Fastest | 42.38% slower | 🔳 |
| map | 🚀 Fastest | 69.63% slower | 4.68% slower |
| match | 🚀 Fastest | 46.75% slower | 🔳 |
| merge | 63.55% slower | 🚀 Fastest | 55.25% slower |
| none | 🚀 Fastest | 98.22% slower | 🔳 |
| omit | 🚀 Fastest | 70.66% slower | 97.56% slower |
| over | 🚀 Fastest | 50.77% slower | 🔳 |
| path | 🚀 Fastest | 74.94% slower | 5.72% slower |
| pick | 🚀 Fastest | 26.29% slower | 86.82% slower |
| prop | 🚀 Fastest | 89.89% slower | 🔳 |
| propEq | 🚀 Fastest | 95.26% slower | 🔳 |
| range | 95.17% slower | 90.22% slower | 🚀 Fastest |
| reduce | 52.76% slower | 74.02% slower | 🚀 Fastest |
| repeat | 85.91% slower | 95.31% slower | 🚀 Fastest |
| replace | 0.47% slower | 28.13% slower | 🚀 Fastest |
| set | 🚀 Fastest | 36.26% slower | 🔳 |
| sort | 🚀 Fastest | 63.15% slower | 🔳 |
| sortBy | 🚀 Fastest | 61.57% slower | 88.88% slower |
| split | 🚀 Fastest | 85.34% slower | 33.69% slower |
| splitEvery | 🚀 Fastest | 90.18% slower | 🔳 |
| take | 93.44% slower | 98.04% slower | 🚀 Fastest |
| takeLast | 92.61% slower | 98.83% slower | 🚀 Fastest |
| test | 🚀 Fastest | 94.42% slower | 🔳 |
| type | 18.91% slower | 🚀 Fastest | 🔳 |
| uniq | 98.98% slower | 96.58% slower | 🚀 Fastest |
| update | 🚀 Fastest | 38.88% slower | 🔳 |
| view | 🚀 Fastest | 82.21% slower | 🔳 |
Used by
API
add
add(a: number, b: number): numberIt adds a and b.
R.add(2, 3) // => 5Try the above R.add example in Rambda REPL
All Typescript definitions
add(a: number, b: number): number;
add(a: number): (b: number) => number;R.add source
export function add(a, b){
if (arguments.length === 1) return _b => add(a, _b)
return Number(a) + Number(b)
}Tests
import { add } from './add'
test('with number', () => {
expect(add(2, 3)).toEqual(5)
expect(add(7)(10)).toEqual(17)
})
test('string is bad input', () => {
expect(add('foo', 'bar')).toBeNaN()
})
test('ramda specs', () => {
expect(add('1', '2')).toEqual(3)
expect(add(1, '2')).toEqual(3)
expect(add(true, false)).toEqual(1)
expect(add(null, null)).toEqual(0)
expect(add(undefined, undefined)).toEqual(NaN)
expect(add(new Date(1), new Date(2))).toEqual(3)
})Typescript test
import {add} from 'rambda'
describe('R.add', () => {
it('happy', () => {
const result = add(4, 1)
result // $ExpectType number
})
it('curried', () => {
const result = add(4)(1)
result // $ExpectType number
})
})adjust
adjust<T>(index: number, replaceFn: (x: T) => T, list: ReadonlyArray<T>): T[]It replaces index in array list with the result of replaceFn(list[i]).
R.adjust(
0,
a => a + 1,
[0, 100]
) // => [1, 100]Try the above R.adjust example in Rambda REPL
All Typescript definitions
adjust<T>(index: number, replaceFn: (x: T) => T, list: ReadonlyArray<T>): T[];
adjust<T>(index: number, replaceFn: (x: T) => T): (list: ReadonlyArray<T>) => T[];R.adjust source
import { curry } from './curry'
function adjustFn(
index, replaceFn, list
){
const actualIndex = index < 0 ? list.length + index : index
if (index >= list.length || actualIndex < 0) return list
const clone = list.slice()
clone[ actualIndex ] = replaceFn(clone[ actualIndex ])
return clone
}
export const adjust = curry(adjustFn)Tests
import { add } from './add'
import { adjust } from './adjust'
import { pipe } from './pipe'
const list = [ 0, 1, 2 ]
const expected = [ 0, 11, 2 ]
test('happy', () => {})
test('happy', () => {
expect(adjust(
1, add(10), list
)).toEqual(expected)
})
test('with curring type 1 1 1', () => {
expect(adjust(1)(add(10))(list)).toEqual(expected)
})
test('with curring type 1 2', () => {
expect(adjust(1)(add(10), list)).toEqual(expected)
})
test('with curring type 2 1', () => {
expect(adjust(1, add(10))(list)).toEqual(expected)
})
test('with negative index', () => {
expect(adjust(
-2, add(10), list
)).toEqual(expected)
})
test('when index is out of bounds', () => {
const list = [ 0, 1, 2, 3 ]
expect(adjust(
4, add(1), list
)).toEqual(list)
expect(adjust(
-5, add(1), list
)).toEqual(list)
})1 failed Ramda.adjust specs
💥 Reason for the failure: Ramda method accepts an array-like object
💥 Reason for the failure: Ramda method accepts an array-like object
var R = require('../../../../dist/rambda.js');
var eq = require('./shared/eq');
describe('adjust', function() {
it('accepts an array-like object', function() {
function args() {
return arguments;
}
eq(R.adjust(2, R.add(1), args(0, 1, 2, 3)), [0, 1, 3, 3]);
});
});all
all<T>(predicate: (x: T, index: number) => boolean, list: ReadonlyArray<T>): booleanIt returns true, if all members of array list returns true, when applied as argument to predicate function.
const list = [ 0, 1, 2, 3, 4 ]
const predicate = x => x > -1
const result = R.all(predicate, arr)
// => trueTry the above R.all example in Rambda REPL
All Typescript definitions
all<T>(predicate: (x: T, index: number) => boolean, list: ReadonlyArray<T>): boolean;
all<T>(predicate: (x: T) => boolean, list: ReadonlyArray<T>): boolean;
all<T>(predicate: (x: T, index: number) => boolean): (list: ReadonlyArray<T>) => boolean;
all<T>(predicate: (x: T) => boolean): (list: ReadonlyArray<T>) => boolean;R.all source
export function all(predicate, list){
if (arguments.length === 1) return _list => all(predicate, _list)
for (let i = 0; i < list.length; i++){
if (!predicate(list[ i ], i)) return false
}
return true
}Tests
import { all } from './all'
const numArr = [ 0, 1, 2, 3, 4 ]
test('when true', () => {
const fn = x => x > -1
expect(all(fn)(numArr)).toBeTrue()
})
test('when false', () => {
const fn = x => x > 2
expect(all(fn, numArr)).toBeFalse()
})
test('pass index as second argument', () => {
const indexes = []
const fn = (x, i) => {
indexes.push(i)
return x > 5
}
all(fn, [ 10, 12, 14 ])
expect(indexes).toEqual([ 0, 1, 2 ])
})Typescript test
import {all} from 'rambda'
describe('all', () => {
it('happy', () => {
const result = all(
x => {
x // $ExpectType number
return x > 0
},
[1, 2, 3]
)
result // $ExpectType boolean
})
it('pass index', () => {
const result = all(
(x, i) => {
x // $ExpectType number
i // $ExpectType number
return x > 0
},
[1, 2, 3]
)
result // $ExpectType boolean
})
it('pass index + curry', () => {
const result = all<number>((x, i) => {
x // $ExpectType number
i // $ExpectType number
return x > 0
})([1, 2, 3])
result // $ExpectType boolean
})
it('curried needs a type', () => {
const result = all<number>(x => {
x // $ExpectType number
return x > 0
})([1, 2, 3])
result // $ExpectType boolean
})
})allPass
allPass<T>(predicates: ((x: T) => boolean)[]): (input: T) => booleanIt returns true, if all functions of predicates return true, when input is their argument.
const input = {
a : 1,
b : 2,
}
const predicates = [
x => x.a === 1,
x => x.b === 2,
]
const result = R.allPass(predicates)(input) // => trueTry the above R.allPass example in Rambda REPL
All Typescript definitions
allPass<T>(predicates: ((x: T) => boolean)[]): (input: T) => boolean;R.allPass source
export function allPass(predicates){
return input => {
let counter = 0
while (counter < predicates.length){
if (!predicates[ counter ](input)){
return false
}
counter++
}
return true
}
}Tests
import { allPass } from './allPass'
test('happy', () => {
const rules = [ x => typeof x === 'number', x => x > 10, x => x * 7 < 100 ]
expect(allPass(rules)(11)).toBeTrue()
expect(allPass(rules)(undefined)).toBeFalse()
})
test('when returns true', () => {
const conditionArr = [ val => val.a === 1, val => val.b === 2 ]
expect(allPass(conditionArr)({
a : 1,
b : 2,
})).toBeTrue()
})
test('when returns false', () => {
const conditionArr = [ val => val.a === 1, val => val.b === 3 ]
expect(allPass(conditionArr)({
a : 1,
b : 2,
})).toBeFalse()
})Typescript test
import {allPass} from 'rambda'
describe('allPass', () => {
it('happy', () => {
const x = allPass<number>([
y => {
y // $ExpectType number
return typeof y === 'number'
},
y => {
return y > 0
},
])(11)
x // $ExpectType boolean
})
})1 failed Ramda.allPass specs
💥 Reason for the failure: Ramda method returns a curried function whose arity matches that of the highest-arity predicate
💥 Reason for the failure: Ramda method returns a curried function whose arity matches that of the highest-arity predicate
var R = require('../../../../dist/rambda.js');
var eq = require('./shared/eq');
describe('allPass', function() {
var odd = function(n) { return n % 2 !== 0; };
var lt20 = function(n) { return n < 20; };
var gt5 = function(n) { return n > 5; };
var plusEq = function(w, x, y, z) { return w + x === y + z; };
it('returns a curried function whose arity matches that of the highest-arity predicate', function() {
eq(R.allPass([odd, gt5, plusEq]).length, 4);
eq(R.allPass([odd, gt5, plusEq])(9, 9, 9, 9), true);
eq(R.allPass([odd, gt5, plusEq])(9)(9)(9)(9), true);
});
});always
always<T>(x: T): () => TIt returns function that always returns x.
const fn = R.always(7)
console.log(fn())// => 7Try the above R.always example in Rambda REPL
All Typescript definitions
always<T>(x: T): () => T;R.always source
export function always(x){
return () => x
}Tests
import { always } from './always'
import { F } from './F'
test('happy', () => {
const fn = always(7)
expect(fn()).toEqual(7)
expect(fn()).toEqual(7)
})
test('f', () => {
const fn = always(F())
expect(fn()).toBeFalse()
expect(fn()).toBeFalse()
})Typescript test
import {always} from 'rambda'
describe('R.always', () => {
it('happy', () => {
const fn = always('foo')
fn // $ExpectType () => string
const result = fn()
result // $ExpectType string
})
})and
and<T extends { and?: ((...a: readonly any[]) => any)Returns true if both arguments are true. Otherwise, it returns false.
R.and(true, true); // => true
R.and(false, true); // => falseTry the above R.and example in Rambda REPL
All Typescript definitions
and<T extends { and?: ((...a: readonly any[]) => any); } | number | boolean | string | null>(fn1: T, val2: any): boolean;
and<T extends { and?: ((...a: readonly any[]) => any); } | number | boolean | string | null>(fn1: T): (val2: any) => boolean;R.and source
export function and(a, b){
if (arguments.length === 1) return _b => and(a, _b)
return a && b
}Tests
import { and } from './and'
test('happy', () => {
expect(and(true, true)).toBeTrue()
expect(and(true)(true)).toBeTrue()
expect(and(4)(2)).toBe(2)
expect(and(true, false)).toBeFalse()
expect(and(false, true)).toBeFalse()
expect(and(false, false)).toBeFalse()
})Typescript test
import {and} from 'rambda'
describe('R.and', () => {
it('happy', () => {
const result = and(true, false)
result // $ExpectType boolean
})
it('curried', () => {
const result = and(true)(false)
result // $ExpectType boolean
})
})any
any<T>(predicate: (x: T, i: number) => boolean, list: ReadonlyArray<T>): booleanIt returns true, if at least one member of list returns true, when passed to predicate function.
const list = [1, 2, 3]
const predicate = x => x * x > 8
R.any(fn, list)
// => trueTry the above R.any example in Rambda REPL
All Typescript definitions
any<T>(predicate: (x: T, i: number) => boolean, list: ReadonlyArray<T>): boolean;
any<T>(predicate: (x: T) => boolean, list: ReadonlyArray<T>): boolean;
any<T>(predicate: (x: T, i: number) => boolean): (list: ReadonlyArray<T>) => boolean;
any<T>(predicate: (x: T) => boolean): (list: ReadonlyArray<T>) => boolean;R.any source
export function any(predicate, list){
if (arguments.length === 1) return _list => any(predicate, _list)
let counter = 0
while (counter < list.length){
if (predicate(list[ counter ], counter)){
return true
}
counter++
}
return false
}Tests
import { any } from './any'
const arr = [ 1, 2 ]
test('no curry', () => {
expect(any(val => val < 0, arr)).toBeFalse()
})
test('with curry', () => {
expect(any(val => val < 2)(arr)).toBeTrue()
})
test('passes index to predicate', () => {
any((x, i) => {
expect(typeof x).toBe('string')
expect(typeof i).toBe('number')
})([ 'foo', 'bar' ])
})Typescript test
import {any} from 'rambda'
describe('R.any', () => {
it('happy', () => {
const result = any(
x => {
x // $ExpectType number
return x > 2
},
[1, 2, 3]
)
result // $ExpectType boolean
})
it('when curried needs a type', () => {
const result = any<number>(x => {
x // $ExpectType number
return x > 2
})([1, 2, 3])
result // $ExpectType boolean
})
it('pass index as second argument', () => {
const result = any(
(x, i) => {
x // $ExpectType number
i // $ExpectType number
return x > 2
},
[1, 2, 3]
)
result // $ExpectType boolean
})
it('pass index as second argument when curried needs a type', () => {
const result = any<number>((x, i) => {
x // $ExpectType number
i // $ExpectType number
return x > 2
})([1, 2, 3])
result // $ExpectType boolean
})
})anyPass
anyPass<T>(predicates: ReadonlyArray<SafePred<T>>): SafePred<T>It accepts list of predicates and returns a function. This function with its input will return true, if any of predicates returns true for this input.
const isBig = x => x > 20
const isOdd = x => x % 2 === 1
const input = 11
const fn = R.anyPass(
[isBig, isOdd]
)
const result = fn(input)
// => trueTry the above R.anyPass example in Rambda REPL
All Typescript definitions
anyPass<T>(predicates: ReadonlyArray<SafePred<T>>): SafePred<T>;R.anyPass source
export function anyPass(predicates){
return input => {
let counter = 0
while (counter < predicates.length){
if (predicates[ counter ](input)){
return true
}
counter++
}
return false
}
}Tests
import { anyPass } from './anyPass'
test('happy', () => {
const rules = [ x => typeof x === 'string', x => x > 10 ]
const predicate = anyPass(rules)
expect(predicate('foo')).toBeTrue()
expect(predicate(6)).toBeFalse()
})
test('happy', () => {
const rules = [ x => typeof x === 'string', x => x > 10 ]
expect(anyPass(rules)(11)).toBeTrue()
expect(anyPass(rules)(undefined)).toBeFalse()
})
const obj = {
a : 1,
b : 2,
}
test('when returns true', () => {
const conditionArr = [ val => val.a === 1, val => val.a === 2 ]
expect(anyPass(conditionArr)(obj)).toBeTrue()
})
test('when returns false + curry', () => {
const conditionArr = [ val => val.a === 2, val => val.b === 3 ]
expect(anyPass(conditionArr)(obj)).toBeFalse()
})
test('happy', () => {
expect(anyPass([])(3)).toEqual(false)
})Typescript test
import {anyPass} from 'rambda'
describe('anyPass', () => {
it('happy', () => {
const x = anyPass<number>([
y => {
y // $ExpectType number
return typeof y === 'number'
},
y => {
return y > 0
},
])(11)
x // $ExpectType boolean
})
})1 failed Ramda.anyPass specs
💥 Reason for the failure: Ramda method returns a curried function whose arity matches that of the highest-arity predicate
💥 Reason for the failure: Ramda method returns a curried function whose arity matches that of the highest-arity predicate
var R = require('../../../../dist/rambda.js');
var eq = require('./shared/eq');
describe('anyPass', function() {
var odd = function(n) { return n % 2 !== 0; };
var gt20 = function(n) { return n > 20; };
var lt5 = function(n) { return n < 5; };
var plusEq = function(w, x, y, z) { return w + x === y + z; };
it('returns a curried function whose arity matches that of the highest-arity predicate', function() {
eq(R.anyPass([odd, lt5, plusEq]).length, 4);
eq(R.anyPass([odd, lt5, plusEq])(6, 7, 8, 9), false);
eq(R.anyPass([odd, lt5, plusEq])(6)(7)(8)(9), false);
});
});append
append<T>(x: T, listOrString: ReadonlyArray<T>): T[]It adds element x at the end of listOrString.
const x = 'foo'
const result = [
R.append(x, 'cherry_'),
R.append(x, ['bar', 'baz'])
]
// => ['cherry_foo', ['bar', 'baz', 'foo']]Try the above R.append example in Rambda REPL
All Typescript definitions
append<T>(x: T, listOrString: ReadonlyArray<T>): T[];
append<T>(x: T): <T>(listOrString: ReadonlyArray<T>) => T[];R.append source
export function append(x, listOrString){
if (arguments.length === 1)
return _listOrString => append(x, _listOrString)
if (typeof listOrString === 'string') return `${ listOrString }${ x }`
const clone = listOrString.slice()
clone.push(x)
return clone
}Tests
import { append } from './append'
import { compose } from './compose'
import { flatten } from './flatten'
import { map } from './map'
test('with strings', () => {
expect(append('o', 'fo')).toEqual('foo')
})
test('with arrays', () => {
expect(append('tests', [ 'write', 'more' ])).toEqual([
'write',
'more',
'tests',
])
})
test('append to empty array', () => {
expect(append('tests', [])).toEqual([ 'tests' ])
})
test('happy', () => {
const result = compose(flatten, map(append(0)))([ [ 1 ], [ 2 ], [ 3 ] ])
expect(result).toEqual([ 1, 0, 2, 0, 3, 0 ])
})
test('should not modify arguments', () => {
const a = [ 1, 2, 3 ]
const b = append(4, a)
expect(a).toEqual([ 1, 2, 3 ])
expect(b).toEqual([ 1, 2, 3, 4 ])
})Typescript test
import {append} from 'rambda'
const list = [1, 2, 3]
describe('R.append', () => {
it('happy', () => {
const result = append(4, list)
result // $ExpectType number[]
})
it('curried', () => {
const result = append(4)(list)
result // $ExpectType number[]
})
})applySpec
applySpec<Spec extends Record<string, (...args: readonly any[]) => any>>(
spec: Spec
): (
...args: Parameters<ValueOfRecord<Spec>>
) => { [Key in keyof Spec]: ReturnType<Spec[Key]> }It returns a curried function with the same arity as the longest function in the spec object. Arguments will be applied to the spec methods recursively.
const spec = {
name: R.path('deeply.nested.firstname')
}
const json = {
deeply: {
nested: {
firstname: 'barry'
}
}
}
const result = R.applySpec(spec, json) // => { name: 'barry' }
// Second example
const getMetrics = R.applySpec({
sum: R.add,
nested: { mul: R.multiply }
})
getMetrics(2, 4)
// => { sum: 6, nested: { mul: 8 } }Try the above R.applySpec example in Rambda REPL
All Typescript definitions
applySpec<Spec extends Record<string, (...args: readonly any[]) => any>>(
spec: Spec
): (
...args: Parameters<ValueOfRecord<Spec>>
) => { [Key in keyof Spec]: ReturnType<Spec[Key]> };
applySpec<T>(spec: any): (...args: readonly any[]) => T;R.applySpec source
import { _isArray } from './_internals/_isArray'
// recursively traverse the given spec object to find the highest arity function
function __findHighestArity(spec, max = 0){
for (const key in spec){
if (spec.hasOwnProperty(key) === false || key === 'constructor') continue
if (typeof spec[ key ] === 'object'){
max = Math.max(max, __findHighestArity(spec[ key ]))
}
if (typeof spec[ key ] === 'function'){
max = Math.max(max, spec[ key ].length)
}
}
return max
}
function __filterUndefined(){
const defined = []
let i = 0
const l = arguments.length
while (i < l){
if (typeof arguments[ i ] === 'undefined') break
defined[ i ] = arguments[ i ]
i++
}
return defined
}
function __applySpecWithArity(
spec, arity, cache
){
const remaining = arity - cache.length
if (remaining === 1)
return x =>
__applySpecWithArity(
spec, arity, __filterUndefined(...cache, x)
)
if (remaining === 2)
return (x, y) =>
__applySpecWithArity(
spec, arity, __filterUndefined(
...cache, x, y
)
)
if (remaining === 3)
return (
x, y, z
) =>
__applySpecWithArity(
spec, arity, __filterUndefined(
...cache, x, y, z
)
)
if (remaining === 4)
return (
x, y, z, a
) =>
__applySpecWithArity(
spec,
arity,
__filterUndefined(
...cache, x, y, z, a
)
)
if (remaining > 4)
return (...args) =>
__applySpecWithArity(
spec, arity, __filterUndefined(...cache, ...args)
)
// handle spec as Array
if (_isArray(spec)){
const ret = []
let i = 0
const l = spec.length
for (; i < l; i++){
// handle recursive spec inside array
if (typeof spec[ i ] === 'object' || _isArray(spec[ i ])){
ret[ i ] = __applySpecWithArity(
spec[ i ], arity, cache
)
}
// apply spec to the key
if (typeof spec[ i ] === 'function'){
ret[ i ] = spec[ i ](...cache)
}
}
return ret
}
// handle spec as Object
const ret = {}
// apply callbacks to each property in the spec object
for (const key in spec){
if (spec.hasOwnProperty(key) === false || key === 'constructor') continue
// apply the spec recursively
if (typeof spec[ key ] === 'object'){
ret[ key ] = __applySpecWithArity(
spec[ key ], arity, cache
)
continue
}
// apply spec to the key
if (typeof spec[ key ] === 'function'){
ret[ key ] = spec[ key ](...cache)
}
}
return ret
}
export function applySpec(spec, ...args){
// get the highest arity spec function, cache the result and pass to __applySpecWithArity
const arity = __findHighestArity(spec)
if (arity === 0){
return () => ({})
}
const toReturn = __applySpecWithArity(
spec, arity, args
)
return toReturn
}Tests
import { applySpec as applySpecRamda, nAry } from 'ramda'
import { add, always, compose, dec, inc, map, path, prop, T } from '../rambda'
import { applySpec } from './applySpec'
test('different than Ramda when bad spec', () => {
const result = applySpec({ sum : { a : 1 } })(1, 2)
const ramdaResult = applySpecRamda({ sum : { a : 1 } })(1, 2)
expect(result).toEqual({})
expect(ramdaResult).toEqual({ sum : { a : {} } })
})
test('works with empty spec', () => {
expect(applySpec({})()).toEqual({})
expect(applySpec([])(1, 2)).toEqual({})
expect(applySpec(null)(1, 2)).toEqual({})
})
test('works with unary functions', () => {
const result = applySpec({
v : inc,
u : dec,
})(1)
const expected = {
v : 2,
u : 0,
}
expect(result).toEqual(expected)
})
test('works with binary functions', () => {
const result = applySpec({ sum : add })(1, 2)
expect(result).toEqual({ sum : 3 })
})
test('works with nested specs', () => {
const result = applySpec({
unnested : always(0),
nested : { sum : add },
})(1, 2)
const expected = {
unnested : 0,
nested : { sum : 3 },
}
expect(result).toEqual(expected)
})
test('works with arrays of nested specs', () => {
const result = applySpec({
unnested : always(0),
nested : [ { sum : add } ],
})(1, 2)
expect(result).toEqual({
unnested : 0,
nested : [ { sum : 3 } ],
})
})
test('works with arrays of spec objects', () => {
const result = applySpec([ { sum : add } ])(1, 2)
expect(result).toEqual([ { sum : 3 } ])
})
test('works with arrays of functions', () => {
const result = applySpec([ map(prop('a')), map(prop('b')) ])([
{
a : 'a1',
b : 'b1',
},
{
a : 'a2',
b : 'b2',
},
])
const expected = [
[ 'a1', 'a2' ],
[ 'b1', 'b2' ],
]
expect(result).toEqual(expected)
})
test('works with a spec defining a map key', () => {
expect(applySpec({ map : prop('a') })({ a : 1 })).toEqual({ map : 1 })
})
test.skip('retains the highest arity', () => {
const f = applySpec({
f1 : nAry(2, T),
f2 : nAry(5, T),
})
expect(f.length).toBe(5)
})
test('returns a curried function', () => {
expect(applySpec({ sum : add })(1)(2)).toEqual({ sum : 3 })
})
// Additional tests
// ============================================
test('arity', () => {
const spec = {
one : x1 => x1,
two : (x1, x2) => x1 + x2,
three : (
x1, x2, x3
) => x1 + x2 + x3,
}
expect(applySpec(
spec, 1, 2, 3
)).toEqual({
one : 1,
two : 3,
three : 6,
})
})
test('arity over 5 arguments', () => {
const spec = {
one : x1 => x1,
two : (x1, x2) => x1 + x2,
three : (
x1, x2, x3
) => x1 + x2 + x3,
four : (
x1, x2, x3, x4
) => x1 + x2 + x3 + x4,
five : (
x1, x2, x3, x4, x5
) => x1 + x2 + x3 + x4 + x5,
}
expect(applySpec(
spec, 1, 2, 3, 4, 5
)).toEqual({
one : 1,
two : 3,
three : 6,
four : 10,
five : 15,
})
})
test('curried', () => {
const spec = {
one : x1 => x1,
two : (x1, x2) => x1 + x2,
three : (
x1, x2, x3
) => x1 + x2 + x3,
}
expect(applySpec(spec)(1)(2)(3)).toEqual({
one : 1,
two : 3,
three : 6,
})
})
test('curried over 5 arguments', () => {
const spec = {
one : x1 => x1,
two : (x1, x2) => x1 + x2,
three : (
x1, x2, x3
) => x1 + x2 + x3,
four : (
x1, x2, x3, x4
) => x1 + x2 + x3 + x4,
five : (
x1, x2, x3, x4, x5
) => x1 + x2 + x3 + x4 + x5,
}
expect(applySpec(spec)(1)(2)(3)(4)(5)).toEqual({
one : 1,
two : 3,
three : 6,
four : 10,
five : 15,
})
})
test('undefined property', () => {
const spec = { prop : path([ 'property', 'doesnt', 'exist' ]) }
expect(applySpec(spec, {})).toEqual({ prop : undefined })
})
test('restructure json object', () => {
const spec = {
id : path('user.id'),
name : path('user.firstname'),
profile : path('user.profile'),
doesntExist : path('user.profile.doesntExist'),
info : { views : compose(inc, prop('views')) },
type : always('playa'),
}
const data = {
user : {
id : 1337,
firstname : 'john',
lastname : 'shaft',
profile : 'shaft69',
},
views : 42,
}
expect(applySpec(spec, data)).toEqual({
id : 1337,
name : 'john',
profile : 'shaft69',
doesntExist : undefined,
info : { views : 43 },
type : 'playa',
})
})Typescript test
import {multiply, applySpec, inc, dec, add} from 'rambda'
describe('applySpec', () => {
it('ramda 1', () => {
const result = applySpec({
v: inc,
u: dec,
})(1)
result // $ExpectType { v: number; u: number; }
})
it('ramda 1', () => {
interface Output {
sum: number,
multiplied: number,
}
const result = applySpec<Output>({
sum: add,
multiplied: multiply,
})(1, 2)
result // $ExpectType Output
})
})assoc
assoc<T, U, K extends string>(prop: K, newValue: T, obj: U): Record<K, T> & UIt makes a shallow clone of obj with setting or overriding the property prop with newValue.
R.assoc('c', 3, {a: 1, b: 2})
//=> {a: 1, b: 2, c: 3}Try the above R.assoc example in Rambda REPL
All Typescript definitions
assoc<T, U, K extends string>(prop: K, newValue: T, obj: U): Record<K, T> & U;
assoc<T, K extends string>(prop: K, newValue: T): <U>(obj: U) => Record<K, T> & U;
assoc<K extends string>(prop: K): <T, U>(newValue: T, obj: U) => Record<K, T> & U;R.assoc source
import { curry } from './curry'
function assocFn(
prop, newValue, obj
){
return Object.assign(
{}, obj, { [ prop ] : newValue }
)
}
export const assoc = curry(assocFn)Tests
import { assoc } from './assoc'
test('adds a key to an empty object', () => {
expect(assoc(
'a', 1, {}
)).toEqual({ a : 1 })
})
test('adds a key to a non-empty object', () => {
expect(assoc(
'b', 2, { a : 1 }
)).toEqual({
a : 1,
b : 2,
})
})
test('adds a key to a non-empty object - curry case 1', () => {
expect(assoc('b', 2)({ a : 1 })).toEqual({
a : 1,
b : 2,
})
})
test('adds a key to a non-empty object - curry case 2', () => {
expect(assoc('b')(2, { a : 1 })).toEqual({
a : 1,
b : 2,
})
})
test('adds a key to a non-empty object - curry case 3', () => {
const result = assoc('b')(2)({ a : 1 })
expect(result).toEqual({
a : 1,
b : 2,
})
})
test('changes an existing key', () => {
expect(assoc(
'a', 2, { a : 1 }
)).toEqual({ a : 2 })
})
test('undefined is considered an empty object', () => {
expect(assoc(
'a', 1, undefined
)).toEqual({ a : 1 })
})
test('null is considered an empty object', () => {
expect(assoc(
'a', 1, null
)).toEqual({ a : 1 })
})
test('value can be null', () => {
expect(assoc(
'a', null, null
)).toEqual({ a : null })
})
test('value can be undefined', () => {
expect(assoc(
'a', undefined, null
)).toEqual({ a : undefined })
})
test('assignment is shallow', () => {
expect(assoc(
'a', { b : 2 }, { a : { c : 3 } }
)).toEqual({ a : { b : 2 } })
})assocPath
assocPath<T, U>(path: Path, newValue: T, obj: U): UIt makes a shallow clone of obj with setting or overriding with newValue the property found with path.
const path = 'b.c'
const newValue = 2
const obj = { a: 1 }
R.assocPath(path, newValue, obj)
// => { a : 1, b : { c : 2 }}Try the above R.assocPath example in Rambda REPL
All Typescript definitions
assocPath<T, U>(path: Path, newValue: T, obj: U): U;
assocPath<T, U>(path: Path, newValue: T): (obj: U) => U;
assocPath<T, U>(path: Path): FunctionToolbelt.Curry<(newValue: T, obj: U) => U>;R.assocPath source
import { _isArray } from './_internals/_isArray'
import { _isInteger } from './_internals/_isInteger'
import { assoc } from './assoc'
import { curry } from './curry'
function assocPathFn(
path, newValue, input
){
const pathArrValue =
typeof path === 'string' ?
path.split('.').map(x => _isInteger(Number(x)) ? Number(x) : x) :
path
if (pathArrValue.length === 0){
return newValue
}
const index = pathArrValue[ 0 ]
if (pathArrValue.length > 1){
const condition =
typeof input !== 'object' ||
input === null ||
!input.hasOwnProperty(index)
const nextinput = condition ?
_isInteger(pathArrValue[ 1 ]) ?
[] :
{} :
input[ index ]
newValue = assocPathFn(
Array.prototype.slice.call(pathArrValue, 1),
newValue,
nextinput
)
}
if (_isInteger(index) && _isArray(input)){
const arr = input.slice()
arr[ index ] = newValue
return arr
}
return assoc(
index, newValue, input
)
}
export const assocPath = curry(assocPathFn)Tests
import { assocPath } from './assocPath'
test('string can be used as path input', () => {
const testObj = {
a : [ { b : 1 }, { b : 2 } ],
d : 3,
}
const result = assocPath(
'a.0.b', 10, testObj
)
const expected = {
a : [ { b : 10 }, { b : 2 } ],
d : 3,
}
expect(result).toEqual(expected)
})
test('bug', () => {
/*
https://github.com/selfrefactor/rambda/issues/524
*/
const state = {}
const withDateLike = assocPath(
[ 'outerProp', '2020-03-10' ],
{ prop : 2 },
state
)
const withNumber = assocPath(
[ 'outerProp', '5' ], { prop : 2 }, state
)
const withDateLikeExpected = { outerProp : { '2020-03-10' : { prop : 2 } } }
const withNumberExpected = { outerProp : { 5 : { prop : 2 } } }
expect(withDateLike).toEqual(withDateLikeExpected)
expect(withNumber).toEqual(withNumberExpected)
})
test('adds a key to an empty object', () => {
expect(assocPath(
[ 'a' ], 1, {}
)).toEqual({ a : 1 })
})
test('adds a key to a non-empty object', () => {
expect(assocPath(
'b', 2, { a : 1 }
)).toEqual({
a : 1,
b : 2,
})
})
test('adds a nested key to a non-empty object', () => {
expect(assocPath(
'b.c', 2, { a : 1 }
)).toEqual({
a : 1,
b : { c : 2 },
})
})
test('adds a nested key to a nested non-empty object - curry case 1', () => {
expect(assocPath('b.d',
3)({
a : 1,
b : { c : 2 },
})).toEqual({
a : 1,
b : {
c : 2,
d : 3,
},
})
})
test('adds a key to a non-empty object - curry case 1', () => {
expect(assocPath('b', 2)({ a : 1 })).toEqual({
a : 1,
b : 2,
})
})
test('adds a nested key to a non-empty object - curry case 1', () => {
expect(assocPath('b.c', 2)({ a : 1 })).toEqual({
a : 1,
b : { c : 2 },
})
})
test('adds a key to a non-empty object - curry case 2', () => {
expect(assocPath('b')(2, { a : 1 })).toEqual({
a : 1,
b : 2,
})
})
test('adds a key to a non-empty object - curry case 3', () => {
const result = assocPath('b')(2)({ a : 1 })
expect(result).toEqual({
a : 1,
b : 2,
})
})
test('changes an existing key', () => {
expect(assocPath(
'a', 2, { a : 1 }
)).toEqual({ a : 2 })
})
test('undefined is considered an empty object', () => {
expect(assocPath(
'a', 1, undefined
)).toEqual({ a : 1 })
})
test('null is considered an empty object', () => {
expect(assocPath(
'a', 1, null
)).toEqual({ a : 1 })
})
test('value can be null', () => {
expect(assocPath(
'a', null, null
)).toEqual({ a : null })
})
test('value can be undefined', () => {
expect(assocPath(
'a', undefined, null
)).toEqual({ a : undefined })
})
test('assignment is shallow', () => {
expect(assocPath(
'a', { b : 2 }, { a : { c : 3 } }
)).toEqual({ a : { b : 2 } })
})
test('empty array as path', () => {
const result = assocPath(
[], 3, {
a : 1,
b : 2,
}
)
expect(result).toEqual(3)
})
test('happy', () => {
const expected = { foo : { bar : { baz : 42 } } }
const result = assocPath(
[ 'foo', 'bar', 'baz' ], 42, { foo : null }
)
expect(result).toEqual(expected)
})Typescript test
import {assocPath} from 'rambda'
describe('R.assocPath', () => {
it('happy', () => {
const result = assocPath(['b'], 2, {a: 1})
result // $ExpectType { a: number; }
})
})both
both(pred1: Pred, pred2: Pred): PredIt returns a function with input argument.
This function will return true, if both firstCondition and secondCondition return true when input is passed as their argument.
const firstCondition = x => x > 10
const secondCondition = x => x < 20
const fn = R.both(secondCondition)
const result = [fn(15), fn(30)]
// => [true, false]Try the above R.both example in Rambda REPL
All Typescript definitions
both(pred1: Pred, pred2: Pred): Pred;
both<T>(pred1: Predicate<T>, pred2: Predicate<T>): Predicate<T>;
both<T>(pred1: Predicate<T>): (pred2: Predicate<T>) => Predicate<T>;
both(pred1: Pred): (pred2: Pred) => Pred;R.both source
export function both(f, g){
if (arguments.length === 1) return _g => both(f, _g)
return (...input) => f(...input) && g(...input)
}Tests
import { both } from './both'
const firstFn = val => val > 0
const secondFn = val => val < 10
test('with curry', () => {
expect(both(firstFn)(secondFn)(17)).toBeFalse()
})
test('without curry', () => {
expect(both(firstFn, secondFn)(7)).toBeTrue()
})
test('with multiple inputs', () => {
const between = function (
a, b, c
){
return a < b && b < c
}
const total20 = function (
a, b, c
){
return a + b + c === 20
}
const fn = both(between, total20)
expect(fn(
5, 7, 8
)).toBeTrue()
})
test('skip evaluation of the second expression', () => {
let effect = 'not evaluated'
const F = function (){
return false
}
const Z = function (){
effect = 'Z got evaluated'
}
both(F, Z)()
expect(effect).toBe('not evaluated')
})Typescript test
import {both} from 'rambda'
describe('R.both', () => {
it('with passed type', () => {
const fn = both<number>(
x => x > 1,
x => x % 2 === 0
)
fn // $ExpectType Predicate<number>
const result = fn(2) // $ExpectType boolean
result // $ExpectType boolean
})
it('with passed type - curried', () => {
const fn = both<number>(x => x > 1)(x => x % 2 === 0)
fn // $ExpectType Predicate<number>
const result = fn(2)
result // $ExpectType boolean
})
it('no type passed', () => {
const fn = both(
x => {
x // $ExpectType any
return x > 1
},
x => {
x // $ExpectType any
return x % 2 === 0
}
)
const result = fn(2)
result // $ExpectType boolean
})
it('no type passed - curried', () => {
const fn = both((x: number) => {
x // $ExpectType number
return x > 1
})((x: number) => {
x // $ExpectType number
return x % 2 === 0
})
const result = fn(2)
result // $ExpectType boolean
})
})1 failed Ramda.both specs
💥 Reason for the failure: Ramda library supports fantasy-land
💥 Reason for the failure: Ramda library supports fantasy-land
var S = require('sanctuary');
var R = require('../../../../dist/rambda.js');
var eq = require('./shared/eq');
describe('both', function() {
it('accepts fantasy-land applicative functors', function() {
var Just = S.Just;
var Nothing = S.Nothing;
eq(R.both(Just(true), Just(true)), Just(true));
eq(R.both(Just(true), Just(false)), Just(false));
eq(R.both(Just(true), Nothing()), Nothing());
eq(R.both(Nothing(), Just(false)), Nothing());
eq(R.both(Nothing(), Nothing()), Nothing());
});
});chain
chain<T, U>(fn: (n: T) => readonly U[], list: readonly T[]): U[]The method is also known as flatMap.
const duplicate = n => [ n, n ]
const list = [ 1, 2, 3 ]
const result = chain(duplicate, list)
// => [ 1, 1, 2, 2, 3, 3 ]Try the above R.chain example in Rambda REPL
All Typescript definitions
chain<T, U>(fn: (n: T) => readonly U[], list: readonly T[]): U[];
chain<T, U>(fn: (n: T) => readonly U[]): (list: readonly T[]) => U[];
chain<X0, X1, R>(fn: (x0: X0, x1: X1) => R, fn1: (x1: X1) => X0): (x1: X1) => R;R.chain source
export function chain(fn, list){
if (arguments.length === 1){
return _list => chain(fn, _list)
}
return [].concat(...list.map(fn))
}Tests
import { chain } from './chain'
const duplicate = n => [ n, n ]
test('happy', () => {
const fn = x => [ x * 2 ]
const list = [ 1, 2, 3 ]
const result = chain(fn, list)
expect(result).toEqual([ 2, 4, 6 ])
})
test('maps then flattens one level', () => {
expect(chain(duplicate, [ 1, 2, 3 ])).toEqual([ 1, 1, 2, 2, 3, 3 ])
})
test('maps then flattens one level - curry', () => {
expect(chain(duplicate)([ 1, 2, 3 ])).toEqual([ 1, 1, 2, 2, 3, 3 ])
})
test('flattens only one level', () => {
const nest = n => [ [ n ] ]
expect(chain(nest, [ 1, 2, 3 ])).toEqual([ [ 1 ], [ 2 ], [ 3 ] ])
})Typescript test
import {chain} from 'rambda'
const list = [1, 2, 3]
const fn = (x: number) => [`${x}`, `${x}`]
describe('R.chain', () => {
it('without passing type', () => {
const result = chain(fn, list)
result // $ExpectType string[]
const resultCurried = chain(fn)(list)
resultCurried // $ExpectType string[]
})
})5 failed Ramda.chain specs
💥 Reason for the failure: Ramda method passes to
chainproperty if available | Ramda library supports fantasy-land
clamp
clamp(min: number, max: number, input: number): numberRestrict a number input to be withing min and max limits.
If input is bigger than max, then the result is max.
If input is smaller than min, then the result is min.
R.clamp(0, 10, 5) //=> 5
R.clamp(0, 10, -1) //=> 0
R.clamp(0, 10, 11) //=> 10Try the above R.clamp example in Rambda REPL
All Typescript definitions
clamp(min: number, max: number, input: number): number;
clamp(min: number, max: number): (input: number) => number;R.clamp source
import { curry } from './curry'
function clampFn(
min, max, input
){
if (min > max){
throw new Error('min must not be greater than max in clamp(min, max, value)')
}
if (input >= min && input <= max) return input
if (input > max) return max
if (input < min) return min
}
export const clamp = curry(clampFn)Tests
import { clamp } from './clamp'
test('when min is greater than max', () => {
expect(() => clamp(
-5, -10, 5
)).toThrowWithMessage(Error,
'min must not be greater than max in clamp(min, max, value)')
})
test('rambda specs', () => {
expect(clamp(
1, 10, 0
)).toEqual(1)
expect(clamp(
3, 12, 1
)).toEqual(3)
expect(clamp(
-15, 3, -100
)).toEqual(-15)
expect(clamp(
1, 10, 20
)).toEqual(10)
expect(clamp(
3, 12, 23
)).toEqual(12)
expect(clamp(
-15, 3, 16
)).toEqual(3)
expect(clamp(
1, 10, 4
)).toEqual(4)
expect(clamp(
3, 12, 6
)).toEqual(6)
expect(clamp(
-15, 3, 0
)).toEqual(0)
})Typescript test
import {clamp} from 'rambda'
describe('R.clamp', () => {
it('happy', () => {
const result = clamp(1, 10, 20)
result // $ExpectType number
})
})clone
clone<T>(input: T): TIt creates a deep copy of the input, which may contain (nested) Arrays and Objects, Numbers, Strings, Booleans and Dates.
const objects = [{a: 1}, {b: 2}];
const objectsClone = R.clone(objects);
const result = [
R.equals(objects, objectsClone),
R.equals(objects[0], objectsClone[0]),
] // => [ true, true ]Try the above R.clone example in Rambda REPL
All Typescript definitions
clone<T>(input: T): T;
clone<T>(input: ReadonlyArray<T>): T[];R.clone source
import { _isArray } from './_internals/_isArray'
export function clone(input){
const out = _isArray(input) ? Array(input.length) : {}
if (input && input.getTime) return new Date(input.getTime())
for (const key in input){
const v = input[ key ]
out[ key ] =
typeof v === 'object' && v !== null ?
v.getTime ?
new Date(v.getTime()) :
clone(v) :
v
}
return out
}Tests
import assert from 'assert'
import { clone } from './clone'
import { equals } from './equals'
test('with array', () => {
const arr = [
{
b : 2,
c : 'foo',
d : [ 1, 2, 3 ],
},
1,
new Date(),
null,
]
expect(clone(arr)).toEqual(arr)
})
test('with object', () => {
const obj = {
a : 1,
b : 2,
c : 3,
d : [ 1, 2, 3 ],
e : new Date(),
}
expect(clone(obj)).toEqual(obj)
})
test('with date', () => {
const date = new Date(
2014, 10, 14, 23, 59, 59, 999
)
const cloned = clone(date)
assert.notStrictEqual(date, cloned)
expect(cloned).toEqual(new Date(
2014, 10, 14, 23, 59, 59, 999
))
expect(cloned.getDay()).toEqual(5)
})
test('with R.equals', () => {
const objects = [ { a : 1 }, { b : 2 } ]
const objectsClone = clone(objects)
const result = [
equals(objects, objectsClone),
equals(objects[ 0 ], objectsClone[ 0 ]),
]
expect(result).toEqual([ true, true ])
})Typescript test
import {clone} from 'rambda'
describe('R.clone', () => {
it('happy', () => {
const obj = {a: 1, b: 2}
const result = clone(obj)
result // $ExpectType { a: number; b: number; }
})
})9 failed Ramda.clone specs
💥 Reason for the failure: Rambda method work only with objects and arrays
💥 Reason for the failure: Rambda method work only with objects and arrays
var assert = require('assert');
var R = require('../../../../dist/rambda.js');
var eq = require('./shared/eq');
describe('deep clone integers, strings and booleans', function() {
it('clones integers', function() {
eq(R.clone(-4), -4);
eq(R.clone(9007199254740991), 9007199254740991);
});
it('clones floats', function() {
eq(R.clone(-4.5), -4.5);
eq(R.clone(0.0), 0.0);
});
it('clones strings', function() {
eq(R.clone('ramda'), 'ramda');
});
it('clones booleans', function() {
eq(R.clone(true), true);
});
});
describe('deep clone objects', function() {
it('clones objects with circular references', function() {
var x = {c: null};
var y = {a: x};
var z = {b: y};
x.c = z;
var clone = R.clone(x);
assert.notStrictEqual(x, clone);
assert.notStrictEqual(x.c, clone.c);
assert.notStrictEqual(x.c.b, clone.c.b);
assert.notStrictEqual(x.c.b.a, clone.c.b.a);
assert.notStrictEqual(x.c.b.a.c, clone.c.b.a.c);
eq(R.keys(clone), R.keys(x));
eq(R.keys(clone.c), R.keys(x.c));
eq(R.keys(clone.c.b), R.keys(x.c.b));
eq(R.keys(clone.c.b.a), R.keys(x.c.b.a));
eq(R.keys(clone.c.b.a.c), R.keys(x.c.b.a.c));
x.c.b = 1;
assert.notDeepEqual(clone.c.b, x.c.b);
});
});
describe('deep clone arrays', function() {
});
describe('deep clone functions', function() {
});
describe('built-in types', function() {
it('clones RegExp object', function() {
R.forEach(function(pattern) {
var clone = R.clone(pattern);
assert.notStrictEqual(clone, pattern);
eq(clone.constructor, RegExp);
eq(clone.source, pattern.source);
eq(clone.global, pattern.global);
eq(clone.ignoreCase, pattern.ignoreCase);
eq(clone.multiline, pattern.multiline);
}, [/x/, /x/g, /x/i, /x/m, /x/gi, /x/gm, /x/im, /x/gim]);
});
});
describe('deep clone deep nested mixed objects', function() {
it('clones array with mutual ref object', function() {
var obj = {a: 1};
var list = [{b: obj}, {b: obj}];
var clone = R.clone(list);
assert.strictEqual(list[0].b, list[1].b);
assert.strictEqual(clone[0].b, clone[1].b);
assert.notStrictEqual(clone[0].b, list[0].b);
assert.notStrictEqual(clone[1].b, list[1].b);
eq(clone[0].b, {a:1});
eq(clone[1].b, {a:1});
obj.a = 2;
eq(clone[0].b, {a:1});
eq(clone[1].b, {a:1});
});
});
describe('deep clone edge cases', function() {
it('nulls, undefineds and empty objects and arrays', function() {
eq(R.clone(null), null);
eq(R.clone(undefined), undefined);
assert.notStrictEqual(R.clone(undefined), null);
var obj = {};
assert.notStrictEqual(R.clone(obj), obj);
var list = [];
assert.notStrictEqual(R.clone(list), list);
});
});
describe('Let `R.clone` use an arbitrary user defined `clone` method', function() {
it('dispatches to `clone` method if present', function() {
function ArbitraryClone(x) { this.value = x; }
ArbitraryClone.prototype.clone = function() { return new ArbitraryClone(this.value); };
var obj = new ArbitraryClone(42);
var arbitraryClonedObj = R.clone(obj);
eq(arbitraryClonedObj, new ArbitraryClone(42));
eq(arbitraryClonedObj instanceof ArbitraryClone, true);
});
});complement
complement(pred: (...args: any[]) => boolean): (...args: any[]) => booleanIt returns inverted version of origin function that accept input as argument.
The return value of inverted is the negative boolean value of origin(input).
const origin = x => x > 5
const inverted = complement(origin)
const result = [
origin(7),
inverted(7)
] => [ true, false ]Try the above R.complement example in Rambda REPL
All Typescript definitions
complement(pred: (...args: any[]) => boolean): (...args: any[]) => boolean;R.complement source
export function complement(fn){
return (...input) => !fn(...input)
}Tests
import { complement } from './complement'
test('happy', () => {
const fn = complement(x => x.length === 0)
expect(fn([ 1, 2, 3 ])).toBeTrue()
})
test('with multiple parameters', () => {
const between = function (
a, b, c
){
return a < b && b < c
}
const f = complement(between)
expect(f(
4, 5, 11
)).toEqual(false)
expect(f(
12, 2, 6
)).toEqual(true)
})Typescript test
import {complement, isNil} from 'rambda'
describe('R.complement', () => {
it('happy', () => {
const fn = complement(isNil)
const result = fn(null)
result // $ExpectType boolean
})
})1 failed Ramda.complement specs
💥 Reason for the failure: Ramda library supports fantasy-land
💥 Reason for the failure: Ramda library supports fantasy-land
var S = require('sanctuary');
var R = require('../../../../dist/rambda.js');
var eq = require('./shared/eq');
describe('complement', function() {
it('accepts fantasy-land functors', function() {
var Just = S.Just;
var Nothing = S.Nothing;
eq(R.complement(Just(true)), Just(false));
eq(R.complement(Just(false)), Just(true));
eq(R.complement(Nothing()), Nothing());
});
});compose
compose<T1>(fn0: () => T1): () => T1It performs right-to-left function composition.
const result = R.compose(
R.map(x => x * 2),
R.filter(x => x > 2)
)([1, 2, 3, 4])
// => [6, 8]Try the above R.compose example in Rambda REPL
All Typescript definitions
compose<T1>(fn0: () => T1): () => T1;
compose<V0, T1>(fn0: (x0: V0) => T1): (x0: V0) => T1;
compose<V0, V1, T1>(fn0: (x0: V0, x1: V1) => T1): (x0: V0, x1: V1) => T1;
compose<V0, V1, V2, T1>(fn0: (x0: V0, x1: V1, x2: V2) => T1): (x0: V0, x1: V1, x2: V2) => T1;
compose<T1, T2>(fn1: (x: T1) => T2, fn0: () => T1): () => T2;
compose<V0, T1, T2>(fn1: (x: T1) => T2, fn0: (x0: V0) => T1): (x0: V0) => T2;
compose<V0, V1, T1, T2>(fn1: (x: T1) => T2, fn0: (x0: V0, x1: V1) => T1): (x0: V0, x1: V1) => T2;
compose<V0, V1, V2, T1, T2>(fn1: (x: T1) => T2, fn0: (x0: V0, x1: V1, x2: V2) => T1): (x0: V0, x1: V1, x2: V2) => T2;
compose<T1, T2, T3>(fn2: (x: T2) => T3, fn1: (x: T1) => T2, fn0: () => T1): () => T3;
compose<V0, T1, T2, T3>(fn2: (x: T2) => T3, fn1: (x: T1) => T2, fn0: (x: V0) => T1): (x: V0) => T3;
compose<V0, V1, T1, T2, T3>(fn2: (x: T2) => T3, fn1: (x: T1) => T2, fn0: (x0: V0, x1: V1) => T1): (x0: V0, x1: V1) => T3;
compose<V0, V1, V2, T1, T2, T3>(fn2: (x: T2) => T3, fn1: (x: T1) => T2, fn0: (x0: V0, x1: V1, x2: V2) => T1): (x0: V0, x1: V1, x2: V2) => T3;
compose<T1, T2, T3, T4>(fn3: (x: T3) => T4, fn2: (x: T2) => T3, fn1: (x: T1) => T2, fn0: () => T1): () => T4;
compose<V0, T1, T2, T3, T4>(fn3: (x: T3) => T4, fn2: (x: T2) => T3, fn1: (x: T1) => T2, fn0: (x: V0) => T1): (x: V0) => T4;
compose<V0, V1, T1, T2, T3, T4>(fn3: (x: T3) => T4, fn2: (x: T2) => T3, fn1: (x: T1) => T2, fn0: (x0: V0, x1: V1) => T1): (x0: V0, x1: V1) => T4;
compose<V0, V1, V2, T1, T2, T3, T4>(fn3: (x: T3) => T4, fn2: (x: T2) => T3, fn1: (x: T1) => T2, fn0: (x0: V0, x1: V1, x2: V2) => T1): (x0: V0, x1: V1, x2: V2) => T4;
compose<T1, T2, T3, T4, T5>(fn4: (x: T4) => T5, fn3: (x: T3) => T4, fn2: (x: T2) => T3, fn1: (x: T1) => T2, fn0: () => T1): () => T5;
compose<V0, T1, T2, T3, T4, T5>(fn4: (x: T4) => T5, fn3: (x: T3) => T4, fn2: (x: T2) => T3, fn1: (x: T1) => T2, fn0: (x: V0) => T1): (x: V0) => T5;
compose<V0, V1, T1, T2, T3, T4, T5>(fn4: (x: T4) => T5, fn3: (x: T3) => T4, fn2: (x: T2) => T3, fn1: (x: T1) => T2, fn0: (x0: V0, x1: V1) => T1): (x0: V0, x1: V1) => T5;
compose<V0, V1, V2, T1, T2, T3, T4, T5>(fn4: (x: T4) => T5, fn3: (x: T3) => T4, fn2: (x: T2) => T3, fn1: (x: T1) => T2, fn0: (x0: V0, x1: V1, x2: V2) => T1): (x0: V0, x1: V1, x2: V2) => T5;
compose<T1, T2, T3, T4, T5, T6>(fn5: (x: T5) => T6, fn4: (x: T4) => T5, fn3: (x: T3) => T4, fn2: (x: T2) => T3, fn1: (x: T1) => T2, fn0: () => T1): () => T6;
compose<V0, T1, T2, T3, T4, T5, T6>(fn5: (x: T5) => T6, fn4: (x: T4) => T5, fn3: (x: T3) => T4, fn2: (x: T2) => T3, fn1: (x: T1) => T2, fn0: (x: V0) => T1): (x: V0) => T6;
compose<V0, V1, T1, T2, T3, T4, T5, T6>(
fn5: (x: T5) => T6,
fn4: (x: T4) => T5,
fn3: (x: T3) => T4,
fn2: (x: T2) => T3,
fn1: (x: T1) => T2,
fn0: (x0: V0, x1: V1) => T1): (x0: V0, x1: V1) => T6;
compose<V0, V1, V2, T1, T2, T3, T4, T5, T6>(
fn5: (x: T5) => T6,
fn4: (x: T4) => T5,
fn3: (x: T3) => T4,
fn2: (x: T2) => T3,
fn1: (x: T1) => T2,
fn0: (x0: V0, x1: V1, x2: V2) => T1): (x0: V0, x1: V1, x2: V2) => T6;R.compose source
export function compose(...fns){
if (fns.length === 0){
throw new Error('compose requires at least one argument')
}
return (...args) => {
const list = fns.slice()
if (list.length > 0){
const fn = list.pop()
let result = fn(...args)
while (list.length > 0){
result = list.pop()(result)
}
return result
}
}
}Tests
import { add } from './add'
import { compose } from './compose'
import { filter } from './filter'
import { last } from './last'
import { map } from './map'
test('happy', () => {
const result = compose(
last, map(add(10)), map(add(1))
)([ 1, 2, 3 ])
expect(result).toEqual(14)
})
test('can accepts initially two arguments', () => {
const result = compose(map(x => x * 2),
(list, limit) => filter(x => x > limit, list))([ 1, 2, 3, 4, false ], 2)
expect(result).toEqual([ 6, 8 ])
})
test('when no arguments is passed', () => {
expect(() => compose()).toThrow('compose requires at least one argument')
})
test('ramda spec', () => {
const f = function (
a, b, c
){
return [ a, b, c ]
}
const g = compose(f)
expect(g(
1, 2, 3
)).toEqual([ 1, 2, 3 ])
})Typescript test
import {add, subtract, compose} from 'rambda'
describe('R.compose', () => {
it('happy', () => {
const result = compose(subtract(11), add(1), add(1))(1)
result // $ExpectType number
})
it('with void', () => {
const result = compose(
() => {},
() => {}
)()
result // $ExpectType void
})
})3 failed Ramda.compose specs
💥 Reason for the failure: Ramda method passes context to functions | Rambda composed functions have no length
💥 Reason for the failure: Ramda method passes context to functions | Rambda composed functions have no length
var assert = require('assert');
var jsv = require('jsverify');
var R = require('../../../../dist/rambda.js');
var eq = require('./shared/eq');
describe('compose', function() {
it('performs right-to-left function composition', function() {
// f :: (String, Number?) -> ([Number] -> [Number])
var f = R.compose(R.map, R.multiply, parseInt);
eq(f.length, 2);
eq(f('10')([1, 2, 3]), [10, 20, 30]);
eq(f('10', 2)([1, 2, 3]), [2, 4, 6]);
});
it('passes context to functions', function() {
function x(val) {
return this.x * val;
}
function y(val) {
return this.y * val;
}
function z(val) {
return this.z * val;
}
var context = {
a: R.compose(x, y, z),
x: 4,
y: 2,
z: 1
};
eq(context.a(5), 40);
});
it('can be applied to one argument', function() {
var f = function(a, b, c) { return [a, b, c]; };
var g = R.compose(f);
eq(g.length, 3);
eq(g(1, 2, 3), [1, 2, 3]);
});
});
describe('compose properties', function() {
jsv.property('composes two functions', jsv.fn(), jsv.fn(), jsv.nat, function(f, g, x) {
return R.equals(R.compose(f, g)(x), f(g(x)));
jsv.property('associative', jsv.fn(), jsv.fn(), jsv.fn(), jsv.nat, function(f, g, h, x) {
var result = f(g(h(x)));
return R.all(R.equals(result), [
R.compose(f, g, h)(x),
R.compose(f, R.compose(g, h))(x),
R.compose(R.compose(f, g), h)(x)
]);
});concat
concat<T>(x: ReadonlyArray<T>, y: ReadonlyArray<T>): T[]It returns a new string or array, which is the result of merging x and y.
R.concat([1, 2])([3, 4]) // => [1, 2, 3, 4]
R.concat('foo', 'bar') // => 'foobar'Try the above R.concat example in Rambda REPL
All Typescript definitions
concat<T>(x: ReadonlyArray<T>, y: ReadonlyArray<T>): T[];
concat<T>(x: ReadonlyArray<T>): (y: ReadonlyArray<T>) => T[];
concat(x: string, y: string): string;
concat(x: string): (y: string) => string;R.concat source
export function concat(x, y){
if (arguments.length === 1) return _y => concat(x, _y)
return typeof x === 'string' ? `${ x }${ y }` : [ ...x, ...y ]
}Tests
import { concat } from './concat'
test('happy', () => {
const arr1 = [ 'a', 'b', 'c' ]
const arr2 = [ 'd', 'e', 'f' ]
const a = concat(arr1, arr2)
const b = concat(arr1)(arr2)
const expectedResult = [ 'a', 'b', 'c', 'd', 'e', 'f' ]
expect(a).toEqual(expectedResult)
expect(b).toEqual(expectedResult)
})
test('with strings', () => {
expect(concat('ABC', 'DEF')).toEqual('ABCDEF')
})Typescript test
import {concat} from 'rambda'
const list1 = [1, 2, 3]
const list2 = [4, 5, 6]
describe('R.concat', () => {
it('happy', () => {
const result = concat(list1, list2)
result // $ExpectType number[]
})
it('curried', () => {
const result = concat(list1)(list2)
result // $ExpectType number[]
})
})1 failed Ramda.concat specs
💥 Reason for the failure: Ramda method pass to concat property if present
💥 Reason for the failure: Ramda method pass to concat property if present
var assert = require('assert');
var R = require('../../../../dist/rambda.js');
var eq = require('./shared/eq');
describe('concat', function() {
var z1 = {
x: 'z1',
concat: function(that) { return this.x + ' ' + that.x; }
};
var z2 = {
x: 'z2'
};
it('delegates to non-String object with a concat method, as second param', function() {
eq(R.concat(z1, z2), 'z1 z2');
});
});cond
cond(conditions: [Pred, (...a: readonly any[]) => any][]): (...a: readonly any[]) => anyIt takes list with conditions and returns a new function fn that expects input as argument.
This function will start evaluating the conditions in order to find the first winner(order of conditions matter).
The winner is this condition, which left side returns true when input is its argument. Then the evaluation of the right side of the winner will be the final result.
If no winner is found, then fn returns undefined.
const fn = R.cond([
[ x => x > 25, R.always('more than 25') ],
[ x => x > 15, R.always('more than 15') ],
[ R.T, x => `${x} is nothing special` ],
])
const result = [
fn(30),
fn(20),
fn(10),
]
// => ['more than 25', 'more than 15', '10 is nothing special']Try the above R.cond example in Rambda REPL
All Typescript definitions
cond(conditions: [Pred, (...a: readonly any[]) => any][]): (...a: readonly any[]) => any;
cond<A, B>(conditions: [SafePred<A>, (...a: readonly A[]) => B][]): (...a: readonly A[]) => B;R.cond source
export function cond(conditions){
return input => {
let done = false
let toReturn
conditions.forEach(([ predicate, resultClosure ]) => {
if (!done && predicate(input)){
done = true
toReturn = resultClosure(input)
}
})
return toReturn
}
}Tests
import { always } from './always'
import { cond } from './cond'
import { equals } from './equals'
import { T } from './T'
test('returns a function', () => {
expect(typeof cond([])).toEqual('function')
})
test('returns a conditional function', () => {
const fn = cond([
[ equals(0), always('water freezes at 0°C') ],
[ equals(100), always('water boils at 100°C') ],
[
T,
function (temp){
return 'nothing special happens at ' + temp + '°C'
},
],
])
expect(fn(0)).toEqual('water freezes at 0°C')
expect(fn(50)).toEqual('nothing special happens at 50°C')
expect(fn(100)).toEqual('water boils at 100°C')
})
test('no winner', () => {
const fn = cond([
[ equals('foo'), always(1) ],
[ equals('bar'), always(2) ],
])
expect(fn('quux')).toEqual(undefined)
})
test('predicates are tested in order', () => {
const fn = cond([
[ T, always('foo') ],
[ T, always('bar') ],
[ T, always('baz') ],
])
expect(fn()).toEqual('foo')
})Typescript test
import {cond, always, equals} from 'rambda'
describe('R.cond', () => {
it('happy', () => {
const fn = cond<number, string>([
[equals(0), always('water freezes at 0°C')],
[equals(100), always('water boils at 100°C')],
[
() => true,
function(temp) {
return 'nothing special happens at ' + temp + '°C'
},
],
])
const result = fn(0)
result // $ExpectType string
})
})2 failed Ramda.cond specs
💥 Reason for the failure: pass to transformer is not applied in Rambda method
💥 Reason for the failure: pass to transformer is not applied in Rambda method
var R = require('../../../../dist/rambda.js');
var eq = require('./shared/eq');
describe('cond', function() {
it('forwards all arguments to predicates and to transformers', function() {
var fn = R.cond([
[function(_, x) { return x === 42; }, function() { return arguments.length; }]
]);
eq(fn(21, 42, 84), 3);
});
it('retains highest predicate arity', function() {
var fn = R.cond([
[R.nAry(2, R.T), R.T],
[R.nAry(3, R.T), R.T],
[R.nAry(1, R.T), R.T]
]);
eq(fn.length, 3);
});
});converge
converge(after: ((...a: readonly any[]) => any), fns: Array<((...a: readonly any[]) => any)>): (...a: readonly any[]) => anyAll Typescript definitions
converge(after: ((...a: readonly any[]) => any), fns: Array<((...a: readonly any[]) => any)>): (...a: readonly any[]) => any;R.converge source
import { curryN } from './curryN'
import { map } from './map'
import { max } from './max'
import { reduce } from './reduce'
export function converge(fn, transformers){
if (arguments.length === 1)
return _transformers => converge(fn, _transformers)
const highestArity = reduce(
(a, b) => max(a, b.length), 0, transformers
)
return curryN(highestArity, function (){
return fn.apply(this,
map(g => g.apply(this, arguments), transformers))
})
}Tests
import { add } from './add'
import { converge } from './converge'
const mult = (a, b) => a * b
const f1 = converge(mult, [ a => a + 1, a => a + 10 ])
const f2 = converge(mult, [ a => a + 1, (a, b) => a + b + 10 ])
const f3 = converge(mult, [ a => a + 1, (
a, b, c
) => a + b + c + 10 ])
test('happy', () => {
expect(f2(6, 7)).toEqual(161)
})
test('passes the results of applying the arguments individually', () => {
const result = converge(mult)([ add(1), add(3) ])(2)
expect(result).toEqual(15)
})
test('returns a function with the length of the longest argument', () => {
expect(f1.length).toEqual(1)
expect(f2.length).toEqual(2)
expect(f3.length).toEqual(3)
})
test('passes context to its functions', () => {
const a = function (x){
return this.f1(x)
}
const b = function (x){
return this.f2(x)
}
const c = function (x, y){
return this.f3(x, y)
}
const d = converge(c, [ a, b ])
const context = {
f1 : add(1),
f2 : add(2),
f3 : add,
}
expect(a.call(context, 1)).toEqual(2)
expect(b.call(context, 1)).toEqual(3)
expect(d.call(context, 1)).toEqual(5)
})
test('works with empty functions list', () => {
const fn = converge(function (){
return arguments.length
}, [])
expect(fn.length).toEqual(0)
expect(fn()).toEqual(0)
})Typescript test
import {converge} from 'rambda'
const mult = (a: number, b: number) => {
return a * b
}
const fn = converge(mult, [
(a: number) => {
return a
},
(a: number, b: number) => {
return b
},
])
describe('R.converge', () => {
it('happy', () => {
const result = fn(2, 3)
const curriedResult = fn(2)(3)
result // $ExpectType any
curriedResult // $ExpectType any
})
})curry
curry(fn: (...args: readonly any[]) => any): (...a: readonly any[]) => anyIt expects a function as input and returns its curried version.
const fn = (a, b, c) => a + b + c
const curried = R.curry(fn)
const sum = curried(1,2)
const result = sum(3) // => 6Try the above R.curry example in Rambda REPL
All Typescript definitions
curry(fn: (...args: readonly any[]) => any): (...a: readonly any[]) => any;R.curry source
export function curry(fn, args = []){
return (..._args) =>
(rest => rest.length >= fn.length ? fn(...rest) : curry(fn, rest))([
...args,
..._args,
])
}Tests
import { curry } from './curry'
test('happy', () => {
const addFourNumbers = (
a, b, c, d
) => a + b + c + d
const curriedAddFourNumbers = curry(addFourNumbers)
const f = curriedAddFourNumbers(1, 2)
const g = f(3)
expect(g(4)).toEqual(10)
})
test('when called with more arguments', () => {
const add = curry((n, n2) => n + n2)
expect(add(
1, 2, 3
)).toEqual(3)
})
test('when called with zero arguments', () => {
const sub = curry((a, b) => a - b)
const s0 = sub()
expect(s0(5, 2)).toEqual(3)
})
test('when called via multiple curry stages', () => {
const join = curry((
a, b, c, d
) => [ a, b, c, d ].join('-'))
const stage1 = join('A')
const stage2 = stage1('B', 'C')
expect(stage2('D')).toEqual('A-B-C-D')
})Typescript test
import {curry} from 'rambda'
function source(a: number, b: number, c: number, d: number) {
void d
return a * b * c
}
describe('R.curry', () => {
it('happy', () => {
const curried = curry(source)
const result1 = curried(1)(2)(3)
const result2 = curried(1, 2)(3)
const result3 = curried(1)(2, 3)
const result4 = curried(1, 2, 3)
result1 // $ExpectType any
result2 // $ExpectType any
result3 // $ExpectType any
result4 // $ExpectType any
})
})3 failed Ramda.curry specs
💥 Reason for the failure: Ramda library support placeholder(R.__)
💥 Reason for the failure: Ramda library support placeholder(R.__)
var R = require('../../../../dist/rambda.js');
var eq = require('./shared/eq');
var jsv = require('jsverify');
var funcN = require('./shared/funcN');
describe('curry', function() {
it('properly reports the length of the curried function', function() {
var f = R.curry(function(a, b, c, d) {return (a + b * c) / d;});
eq(f.length, 4);
var g = f(12);
eq(g.length, 3);
var h = g(3);
eq(h.length, 2);
eq(g(3, 6).length, 1);
});
it('preserves context', function() {
var ctx = {x: 10};
var f = function(a, b) { return a + b * this.x; };
var g = R.curry(f);
eq(g.call(ctx, 2, 4), 42);
eq(g.call(ctx, 2).call(ctx, 4), 42);
});
it('supports R.__ placeholder', function() {
var f = function(a, b, c) { return [a, b, c]; };
var g = R.curry(f);
var _ = R.__;
eq(g(1)(2)(3), [1, 2, 3]);
eq(g(1)(2, 3), [1, 2, 3]);
eq(g(1, 2)(3), [1, 2, 3]);
eq(g(1, 2, 3), [1, 2, 3]);
eq(g(_, 2, 3)(1), [1, 2, 3]);
eq(g(1, _, 3)(2), [1, 2, 3]);
eq(g(1, 2, _)(3), [1, 2, 3]);
eq(g(1, _, _)(2)(3), [1, 2, 3]);
eq(g(_, 2, _)(1)(3), [1, 2, 3]);
eq(g(_, _, 3)(1)(2), [1, 2, 3]);
eq(g(1, _, _)(2, 3), [1, 2, 3]);
eq(g(_, 2, _)(1, 3), [1, 2, 3]);
eq(g(_, _, 3)(1, 2), [1, 2, 3]);
eq(g(1, _, _)(_, 3)(2), [1, 2, 3]);
eq(g(_, 2, _)(_, 3)(1), [1, 2, 3]);
eq(g(_, _, 3)(_, 2)(1), [1, 2, 3]);
eq(g(_, _, _)(_, _)(_)(1, 2, 3), [1, 2, 3]);
eq(g(_, _, _)(1, _, _)(_, _)(2, _)(_)(3), [1, 2, 3]);
});
it('supports @@functional/placeholder', function() {
var f = function(a, b, c) { return [a, b, c]; };
var g = R.curry(f);
var _ = {'@@functional/placeholder': true, x: Math.random()};
eq(g(1)(2)(3), [1, 2, 3]);
eq(g(1)(2, 3), [1, 2, 3]);
eq(g(1, 2)(3), [1, 2, 3]);
eq(g(1, 2, 3), [1, 2, 3]);
eq(g(_, 2, 3)(1), [1, 2, 3]);
eq(g(1, _, 3)(2), [1, 2, 3]);
eq(g(1, 2, _)(3), [1, 2, 3]);
eq(g(1, _, _)(2)(3), [1, 2, 3]);
eq(g(_, 2, _)(1)(3), [1, 2, 3]);
eq(g(_, _, 3)(1)(2), [1, 2, 3]);
eq(g(1, _, _)(2, 3), [1, 2, 3]);
eq(g(_, 2, _)(1, 3), [1, 2, 3]);
eq(g(_, _, 3)(1, 2), [1, 2, 3]);
eq(g(1, _, _)(_, 3)(2), [1, 2, 3]);
eq(g(_, 2, _)(_, 3)(1), [1, 2, 3]);
eq(g(_, _, 3)(_, 2)(1), [1, 2, 3]);
eq(g(_, _, _)(_, _)(_)(1, 2, 3), [1, 2, 3]);
eq(g(_, _, _)(1, _, _)(_, _)(2, _)(_)(3), [1, 2, 3]);
});
});
describe('curry properties', function() {
jsv.property('curries multiple values', funcN(4), jsv.json, jsv.json, jsv.json, jsv.json, function(f, a, b, c, d) {
var g = R.curry(f);
return R.all(R.equals(f(a, b, c, d)), [
g(a, b, c, d),
g(a)(b)(c)(d),
g(a)(b, c, d),
g(a, b)(c, d),
g(a, b, c)(d)
]);
jsv.property('curries with placeholder', funcN(3), jsv.json, jsv.json, jsv.json, function(f, a, b, c) {
var _ = {'@@functional/placeholder': true, x: Math.random()};
var g = R.curry(f);
return R.all(R.equals(f(a, b, c)), [
g(_, _, c)(a, b),
g(a, _, c)(b),
g(_, b, c)(a),
g(a, _, _)(_, c)(b),
g(a, b, _)(c)
]);
});curryN
curryN(length: number, fn: (...args: readonly any[]) => any): (...a: readonly any[]) => anyIt returns a curried equivalent of the provided function, with the specified arity.
All Typescript definitions
curryN(length: number, fn: (...args: readonly any[]) => any): (...a: readonly any[]) => any;R.curryN source
function _curryN(
n, cache, fn
){
return function (){
let ci = 0
let ai = 0
const cl = cache.length
const al = arguments.length
const args = new Array(cl + al)
while (ci < cl){
args[ ci ] = cache[ ci ]
ci++
}
while (ai < al){
args[ cl + ai ] = arguments[ ai ]
ai++
}
const remaining = n - args.length
return args.length >= n ?
fn.apply(this, args) :
_arity(remaining, _curryN(
n, args, fn
))
}
}
function _arity(n, fn){
switch (n){
case 0:
return function (){
return fn.apply(this, arguments)
}
case 1:
return function (_1){
return fn.apply(this, arguments)
}
case 2:
return function (_1, _2){
return fn.apply(this, arguments)
}
case 3:
return function (
_1, _2, _3
){
return fn.apply(this, arguments)
}
case 4:
return function (
_1, _2, _3, _4
){
return fn.apply(this, arguments)
}
case 5:
return function (
_1, _2, _3, _4, _5
){
return fn.apply(this, arguments)
}
case 6:
return function (
_1, _2, _3, _4, _5, _6
){
return fn.apply(this, arguments)
}
case 7:
return function (
_1, _2, _3, _4, _5, _6, _7
){
return fn.apply(this, arguments)
}
case 8:
return function (
_1, _2, _3, _4, _5, _6, _7, _8
){
return fn.apply(this, arguments)
}
case 9:
return function (
_1, _2, _3, _4, _5, _6, _7, _8, _9
){
return fn.apply(this, arguments)
}
case 10:
return function (
_1, _2, _3, _4, _5, _6, _7, _8, _9, _10
){
return fn.apply(this, arguments)
}
default:
throw new Error('First argument to _arity must be a non-negative integer no greater than ten')
}
}
export function curryN(n, fn){
if (arguments.length === 1) return _fn => curryN(n, _fn)
return _arity(n, _curryN(
n, [], fn
))
}Tests
import { curryN } from './curryN'
function source(
a, b, c, d
){
void d
return a * b * c
}
test('accepts an arity', () => {
const curried = curryN(3, source)
expect(curried(1)(2)(3)).toEqual(6)
expect(curried(1, 2)(3)).toEqual(6)
expect(curried(1)(2, 3)).toEqual(6)
expect(curried(
1, 2, 3
)).toEqual(6)
})
test('can be partially applied', () => {
const curry3 = curryN(3)
const curried = curry3(source)
expect(curried.length).toEqual(3)
expect(curried(1)(2)(3)).toEqual(6)
expect(curried(1, 2)(3)).toEqual(6)
expect(curried(1)(2, 3)).toEqual(6)
expect(curried(
1, 2, 3
)).toEqual(6)
})
test('preserves context', () => {
const ctx = { x : 10 }
const f = function (a, b){
return a + b * this.x
}
const g = curryN(2, f)
expect(g.call(
ctx, 2, 4
)).toEqual(42)
expect(g.call(ctx, 2).call(ctx, 4)).toEqual(42)
})
test('forwards extra arguments', () => {
const f = function (){
return Array.prototype.slice.call(arguments)
}
const g = curryN(3, f)
expect(g(
1, 2, 3
)).toEqual([ 1, 2, 3 ])
expect(g(
1, 2, 3, 4
)).toEqual([ 1, 2, 3, 4 ])
expect(g(1, 2)(3, 4)).toEqual([ 1, 2, 3, 4 ])
expect(g(1)(
2, 3, 4
)).toEqual([ 1, 2, 3, 4 ])
expect(g(1)(2)(3, 4)).toEqual([ 1, 2, 3, 4 ])
})Typescript test
import {curryN} from 'ramda'
function source(a: number, b: number, c: number, d: number) {
void d
return a * b * c
}
describe('R.curryN', () => {
it('happy', () => {
const curried = curryN(3, source)
const result1 = curried(1)(2)(3)
const result2 = curried(1, 2)(3)
const result3 = curried(1)(2, 3)
const result4 = curried(1, 2, 3)
result1 // $ExpectType any
result2 // $ExpectType any
result3 // $ExpectType any
result4 // $ExpectType any
})
})dec
dec(x: number): numberIt decrements a number.
All Typescript definitions
dec(x: number): number;R.dec source
export const dec = x => x - 1Tests
import { dec } from './dec'
test('happy', () => {
expect(dec(2)).toBe(1)
})defaultTo
defaultTo<T>(defaultValue: T): (...inputArguments: (T | null | undefined)[]) => TIt returns defaultValue, if all of inputArguments are undefined, null or NaN.
Else, it returns the first truthy inputArguments instance(from left to right).
// With single input argument
R.defaultTo('foo', 'bar') // => 'bar'
R.defaultTo('foo', undefined) // => 'foo'
// With multiple input arguments
R.defaultTo('foo', undefined, null, NaN) // => 'foo'
R.defaultTo('foo', undefined, 'bar', NaN, 'qux') // => 'bar'
R.defaultTo('foo', undefined, null, NaN, 'quz') // => 'qux'Try the above R.defaultTo example in Rambda REPL
All Typescript definitions
defaultTo<T>(defaultValue: T): (...inputArguments: (T | null | undefined)[]) => T;
defaultTo<T>(defaultValue: T, ...inputArguments: (T | null | undefined)[]): T;
defaultTo<T, U>(defaultValue: T | U, ...inputArguments: (T | U | null | undefined)[]): T | U;R.defaultTo source
function flagIs(inputArguments){
return (
inputArguments === undefined ||
inputArguments === null ||
Number.isNaN(inputArguments) === true
)
}
export function defaultTo(defaultArgument, ...inputArguments){
if (arguments.length === 1){
return (..._inputArguments) =>
defaultTo(defaultArgument, ..._inputArguments)
}
const limit = inputArguments.length - 1
let len = limit + 1
let ready = false
let holder
while (!ready){
const instance = inputArguments[ limit - len + 1 ]
if (len === 0){
ready = true
} else if (flagIs(instance)){
len -= 1
} else {
holder = instance
ready = true
}
}
return holder === undefined ? defaultArgument : holder
}Tests
import { defaultTo } from './defaultTo'
test('with undefined', () => {
expect(defaultTo('foo')(undefined)).toEqual('foo')
})
test('with null', () => {
expect(defaultTo('foo')(null)).toEqual('foo')
})
test('with NaN', () => {
expect(defaultTo('foo')(NaN)).toEqual('foo')
})
test('with empty string', () => {
expect(defaultTo('foo', '')).toEqual('')
})
test('with false', () => {
expect(defaultTo('foo', false)).toEqual(false)
})
test('when inputArgument passes initial check', () => {
expect(defaultTo('foo', 'bar')).toEqual('bar')
})
test('default extends to indefinite input arguments - case 1', () => {
const result = defaultTo(
'foo', null, 'bar'
)
const expected = 'bar'
expect(result).toEqual(expected)
})
test('default extends to indefinite input arguments - case 2', () => {
const result = defaultTo(
'foo', null, NaN, 'bar'
)
const expected = 'bar'
expect(result).toEqual(expected)
})
test('default extends to indefinite input arguments - case 3', () => {
const result = defaultTo(
'foo', null, NaN, undefined
)
const expected = 'foo'
expect(result).toEqual(expected)
})
test('default extends to indefinite input arguments - case 4', () => {
const result = defaultTo(
'foo', null, NaN, undefined, 'bar'
)
const expected = 'bar'
expect(result).toEqual(expected)
})
test('default extends to indefinite input arguments - case 5', () => {
const result = defaultTo(
'foo', null, NaN, 'bar', 'baz'
)
const expected = 'bar'
expect(result).toEqual(expected)
})
test('default extends to indefinite input arguments - case 6', () => {
const result = defaultTo(
'foo', null, NaN, undefined, null, NaN
)
const expected = 'foo'
expect(result).toEqual(expected)
})Typescript test
import {defaultTo} from 'rambda'
describe('R.defaultTo with Ramda spec', () => {
it('input is falsy', () => {
const result = defaultTo('foo', undefined)
result // $ExpectType "foo"
})
it('input is truthy', () => {
const result = defaultTo('foo', 'bar')
result // $ExpectType "foo" | "bar"
})
})
describe('R.defaultTo can have many inputs', () => {
it('happy', () => {
const result = defaultTo('foo', undefined, 'bar')
result // $ExpectType "foo" | "bar"
})
it('curried', () => {
const result = defaultTo('foo')(undefined, 'bar')
result // $ExpectType string
})
it('with two possible types', () => {
const result = defaultTo<string, number>(
'foo',
undefined,
1,
null,
2,
'bar'
)
result // $ExpectType string | number
})
})difference
difference<T>(a: ReadonlyArray<T>, b: ReadonlyArray<T>): T[]It returns the uniq set of all elements in the first list a not contained in the second list b.
const a = [ 1, 2, 3, 4 ]
const b = [ 3, 4, 5, 6 ]
const result = difference(a, b)
// => [ 1, 2 ]Try the above R.difference example in Rambda REPL
All Typescript definitions
difference<T>(a: ReadonlyArray<T>, b: ReadonlyArray<T>): T[];
difference<T>(a: ReadonlyArray<T>): (b: ReadonlyArray<T>) => T[];R.difference source
import { includes } from './includes'
import { uniq } from './uniq'
export function difference(a, b){
if (arguments.length === 1) return _b => difference(a, _b)
return uniq(a).filter(aInstance => !includes(aInstance, b))
}Tests
import { difference } from './difference'
test('difference', () => {
const a = [ 1, 2, 3, 4 ]
const b = [ 3, 4, 5, 6 ]
expect(difference(a)(b)).toEqual([ 1, 2 ])
expect(difference([], [])).toEqual([])
})
test('difference with objects', () => {
const a = [ { id : 1 }, { id : 2 }, { id : 3 }, { id : 4 } ]
const b = [ { id : 3 }, { id : 4 }, { id : 5 }, { id : 6 } ]
expect(difference(a, b)).toEqual([ { id : 1 }, { id : 2 } ])
})
test('no duplicates in first list', () => {
const M2 = [ 1, 2, 3, 4, 1, 2, 3, 4 ]
const N2 = [ 3, 3, 4, 4, 5, 5, 6, 6 ]
expect(difference(M2, N2)).toEqual([ 1, 2 ])
})
test('should use R.equals', () => {
expect(difference([ NaN ], [ NaN ]).length).toEqual(0)
})Typescript test
import {difference} from 'rambda'
const list1 = [1, 2, 3]
const list2 = [1, 2, 4]
describe('R.difference', () => {
it('happy', () => {
const result = difference(list1, list2)
result // $ExpectType number[]
})
it('curried', () => {
const result = difference(list1)(list2)
result // $ExpectType number[]
})
})dissoc
dissoc<T>(prop: string, obj: any): TIt returns a new object that does not contain property prop.
R.dissoc('b', {a: 1, b: 2, c: 3})
//=> {a: 1, c: 3}Try the above R.dissoc example in Rambda REPL
All Typescript definitions
dissoc<T>(prop: string, obj: any): T;
dissoc<T>(prop: string): (obj: any) => T;R.dissoc source
export function dissoc(prop, obj){
if (arguments.length === 1) return _obj => dissoc(prop, _obj)
if (obj === null || obj === undefined) return {}
const willReturn = {}
for (const p in obj){
willReturn[ p ] = obj[ p ]
}
delete willReturn[ prop ]
return willReturn
}Tests
import { dissoc } from './dissoc'
test('input is null or undefined', () => {
expect(dissoc('b', null)).toEqual({})
expect(dissoc('b', undefined)).toEqual({})
})
test('property exists curried', () => {
expect(dissoc('b')({
a : 1,
b : 2,
})).toEqual({ a : 1 })
})
test('property doesn\'t exists', () => {
expect(dissoc('c', {
a : 1,
b : 2,
})).toEqual({
a : 1,
b : 2,
})
})
test('works with non-string property', () => {
expect(dissoc(42, {
a : 1,
42 : 2,
})).toEqual({ a : 1 })
expect(dissoc(null, {
a : 1,
null : 2,
})).toEqual({ a : 1 })
expect(dissoc(undefined, {
a : 1,
undefined : 2,
})).toEqual({ a : 1 })
})
test('includes prototype properties', () => {
function Rectangle(width, height){
this.width = width
this.height = height
}
const area = Rectangle.prototype.area = function (){
return this.width * this.height
}
const rect = new Rectangle(7, 6)
expect(dissoc('area', rect)).toEqual({
width : 7,
height : 6,
})
expect(dissoc('width', rect)).toEqual({
height : 6,
area : area,
})
expect(dissoc('depth', rect)).toEqual({
width : 7,
height : 6,
area : area,
})
})Typescript test
import {dissoc, pipe, identity} from 'rambda'
const obj = {
a: 1,
b: 2,
}
interface Output {
a: string,
}
describe('R.dissoc', () => {
it('happy', () => {
const result = dissoc<Output>('b', obj)
result // $ExpectType Output
})
it('curried', () => {
const result = dissoc<Output>('b')(obj)
result // $ExpectType Output
})
it('within R.pipe', () => {
const result = pipe<object, object, Output>(identity, dissoc('b'))(obj)
result // $ExpectType Output
})
})divide
divide(x: number, y: number): numberR.divide(71, 100) // => 0.71Try the above R.divide example in Rambda REPL
All Typescript definitions
divide(x: number, y: number): number;
divide(x: number): (y: number) => number;R.divide source
export function divide(a, b){
if (arguments.length === 1) return _b => divide(a, _b)
return a / b
}Tests
import { divide } from './divide'
test('happy', () => {
expect(divide(71, 100)).toEqual(0.71)
expect(divide(71)(100)).toEqual(0.71)
})drop
drop<T>(howMany: number, listOrString: ReadonlyArray<T>): T[]It returns listOrString with howMany items dropped from its beginning.
R.drop(2, ['foo', 'bar', 'baz']) // => ['baz']
R.drop(2, 'foobar') // => 'obar'Try the above R.drop example in Rambda REPL
All Typescript definitions
drop<T>(howMany: number, listOrString: ReadonlyArray<T>): T[];
drop(howMany: number, listOrString: string): string;
drop<T>(howMany: number): {
<T>(listOrString: readonly T[]): T[];
(listOrString: string): string;
};R.drop source
export function drop(howManyToDrop, listOrString){
if (arguments.length === 1) return _list => drop(howManyToDrop, _list)
return listOrString.slice(howManyToDrop > 0 ? howManyToDrop : 0)
}Tests
import assert from 'assert'
import { drop } from './drop'
test('with array', () => {
expect(drop(2)([ 'foo', 'bar', 'baz' ])).toEqual([ 'baz' ])
expect(drop(3, [ 'foo', 'bar', 'baz' ])).toEqual([])
expect(drop(4, [ 'foo', 'bar', 'baz' ])).toEqual([])
})
test('with string', () => {
expect(drop(3, 'rambda')).toEqual('bda')
})
test('with non-positive count', () => {
expect(drop(0, [ 1, 2, 3 ])).toEqual([ 1, 2, 3 ])
expect(drop(-1, [ 1, 2, 3 ])).toEqual([ 1, 2, 3 ])
expect(drop(-Infinity, [ 1, 2, 3 ])).toEqual([ 1, 2, 3 ])
})
test('should return copy', () => {
const xs = [ 1, 2, 3 ]
assert.notStrictEqual(drop(0, xs), xs)
assert.notStrictEqual(drop(-1, xs), xs)
})Typescript test
import {drop} from 'rambda'
const list = [1, 2, 3, 4]
const str = 'foobar'
const howMany = 2
describe('R.drop - array', () => {
it('happy', () => {
const result = drop(howMany, list)
result // $ExpectType number[]
})
it('curried', () => {
const result = drop(howMany)(list)
result // $ExpectType number[]
})
})
describe('R.drop - string', () => {
it('happy', () => {
const result = drop(howMany, str)
result // $ExpectType string
})
it('curried', () => {
const result = drop(howMany)(str)
result // $ExpectType string
})
})dropLast
dropLast<T>(howMany: number, listOrString: ReadonlyArray<T>): T[]It returns listOrString with howMany items dropped from its end.
R.dropLast(2, ['foo', 'bar', 'baz']) // => ['foo']
R.dropLast(2, 'foobar') // => 'foob'Try the above R.dropLast example in Rambda REPL
All Typescript definitions
dropLast<T>(howMany: number, listOrString: ReadonlyArray<T>): T[];
dropLast(howMany: number, listOrString: string): string;
dropLast<T>(howMany: number): {
<T>(listOrString: readonly T[]): T[];
(listOrString: string): string;
};R.dropLast source
export function dropLast(howManyToDrop, listOrString){
if (arguments.length === 1){
return _listOrString => dropLast(howManyToDrop, _listOrString)
}
return howManyToDrop > 0 ?
listOrString.slice(0, -howManyToDrop) :
listOrString.slice()
}Tests
import assert from 'assert'
import { dropLast } from './dropLast'
test('with array', () => {
expect(dropLast(2)([ 'foo', 'bar', 'baz' ])).toEqual([ 'foo' ])
expect(dropLast(3, [ 'foo', 'bar', 'baz' ])).toEqual([])
expect(dropLast(4, [ 'foo', 'bar', 'baz' ])).toEqual([])
})
test('with string', () => {
expect(dropLast(3, 'rambda')).toEqual('ram')
})
test('with non-positive count', () => {
expect(dropLast(0, [ 1, 2, 3 ])).toEqual([ 1, 2, 3 ])
expect(dropLast(-1, [ 1, 2, 3 ])).toEqual([ 1, 2, 3 ])
expect(dropLast(-Infinity, [ 1, 2, 3 ])).toEqual([ 1, 2, 3 ])
})
test('should return copy', () => {
const xs = [ 1, 2, 3 ]
assert.notStrictEqual(dropLast(0, xs), xs)
assert.notStrictEqual(dropLast(-1, xs), xs)
})Typescript test
import {dropLast} from 'rambda'
const list = [1, 2, 3, 4]
const str = 'foobar'
const howMany = 2
describe('R.dropLast - array', () => {
it('happy', () => {
const result = dropLast(howMany, list)
result // $ExpectType number[]
})
it('curried', () => {
const result = dropLast(howMany)(list)
result // $ExpectType number[]
})
})
describe('R.dropLast - string', () => {
it('happy', () => {
const result = dropLast(howMany, str)
result // $ExpectType string
})
it('curried', () => {
const result = dropLast(howMany)(str)
result // $ExpectType string
})
})5 failed Ramda.dropLast specs
💥 Reason for the failure: Ramda method can act as a transducer
💥 Reason for the failure: Ramda method can act as a transducer
var assert = require('assert');
var R = require('../../../../dist/rambda.js');
var eq = require('./shared/eq');
describe('dropLast', function() {
it('can act as a transducer', function() {
var dropLast2 = R.dropLast(2);
assert.deepEqual(R.into([], dropLast2, [1, 3, 5, 7, 9, 1, 2]), [1, 3, 5, 7, 9]);
assert.deepEqual(R.into([], dropLast2, [1]), []);
});
});either
either(firstPredicate: Pred, secondPredicate: Pred): PredIt returns a new predicate function from firstPredicate and secondPredicate inputs.
This predicate function will return true, if any of the two input predicates return true.
const firstPredicate = x => x > 10
const secondPredicate = x => x % 2 === 0
const predicate = R.either(firstPredicate, secondPredicate)
const result = [
predicate(15),
predicate(8),
predicate(7),
]
//=> [true, true, false]Try the above R.either example in Rambda REPL
All Typescript definitions
either(firstPredicate: Pred, secondPredicate: Pred): Pred;
either<T>(firstPredicate: Predicate<T>, secondPredicate: Predicate<T>): Predicate<T>;
either<T>(firstPredicate: Predicate<T>): (secondPredicate: Predicate<T>) => Predicate<T>;
either(firstPredicate: Pred): (secondPredicate: Pred) => Pred;R.either source
export function either(firstPredicate, secondPredicate){
if (arguments.length === 1){
return _secondPredicate => either(firstPredicate, _secondPredicate)
}
return (...input) =>
Boolean(firstPredicate(...input) || secondPredicate(...input))
}Tests
import { either } from './either'
test('with multiple inputs', () => {
const between = function (
a, b, c
){
return a < b && b < c
}
const total20 = function (
a, b, c
){
return a + b + c === 20
}
const fn = either(between, total20)
expect(fn(
7, 8, 5
)).toBeTrue()
})
test('skip evaluation of the second expression', () => {
let effect = 'not evaluated'
const F = function (){
return true
}
const Z = function (){
effect = 'Z got evaluated'
}
either(F, Z)()
expect(effect).toBe('not evaluated')
})
test('case 1', () => {
const firstFn = val => val > 0
const secondFn = val => val * 5 > 10
expect(either(firstFn, secondFn)(1)).toBeTrue()
})
test('case 2', () => {
const firstFn = val => val > 0
const secondFn = val => val === -10
const fn = either(firstFn)(secondFn)
expect(fn(-10)).toBeTrue()
})Typescript test
import {either} from 'rambda'
describe('R.either', () => {
it('with passed type', () => {
const fn = either<number>(
x => x > 1,
x => x % 2 === 0
)
fn // $ExpectType Predicate<number>
const result = fn(2) // $ExpectType boolean
result // $ExpectType boolean
})
it('with passed type - curried', () => {
const fn = either<number>(x => x > 1)(x => x % 2 === 0)
fn // $ExpectType Predicate<number>
const result = fn(2)
result // $ExpectType boolean
})
it('no type passed', () => {
const fn = either(
x => {
x // $ExpectType any
return x > 1
},
x => {
x // $ExpectType any
return x % 2 === 0
}
)
const result = fn(2)
result // $ExpectType boolean
})
it('no type passed - curried', () => {
const fn = either((x: number) => {
x // $ExpectType number
return x > 1
})((x: number) => {
x // $ExpectType number
return x % 2 === 0
})
const result = fn(2)
result // $ExpectType boolean
})
})1 failed Ramda.either specs
💥 Reason for the failure: Ramda library supports fantasy-land
💥 Reason for the failure: Ramda library supports fantasy-land
var S = require('sanctuary');
var R = require('../../../../dist/rambda.js');
var eq = require('./shared/eq');
describe('either', function() {
it('accepts fantasy-land applicative functors', function() {
var Just = S.Just;
var Nothing = S.Nothing;
eq(R.either(Just(true), Just(true)), Just(true));
eq(R.either(Just(true), Just(false)), Just(true));
eq(R.either(Just(false), Just(false)), Just(false));
eq(R.either(Just(true), Nothing()), Nothing());
eq(R.either(Nothing(), Just(false)), Nothing());
eq(R.either(Nothing(), Nothing()), Nothing());
});
});endsWith
endsWith(target: string, str: string): booleanCurried version of String.prototype.endsWith
const str = 'foo-bar'
const target = '-bar'
const result = R.endsWith(target, str)
// => trueTry the above R.endsWith example in Rambda REPL
All Typescript definitions
endsWith(target: string, str: string): boolean;
endsWith(target: string): (str: string) => boolean;R.endsWith source
export function endsWith(target, str){
if (arguments.length === 1) return _str => endsWith(target, _str)
return str.endsWith(target)
}Tests
import { endsWith } from './endsWith'
test('happy', () => {
expect(endsWith('bar', 'foo-bar')).toBeTrue()
expect(endsWith('baz')('foo-bar')).toBeFalse()
})
test('does not work with arrays', () => {
expect(() => endsWith([ 'c' ], [ 'a', 'b', 'c' ])).toThrowWithMessage(Error,
'str.endsWith is not a function')
})Typescript test
import {endsWith} from 'rambda'
const target = 'foo'
const input = 'foo bar'
describe('R.endsWith', () => {
it('happy', () => {
const result = endsWith(target, input)
result // $ExpectType boolean
})
it('curried', () => {
const result = endsWith(target)(input)
result // $ExpectType boolean
})
})4 failed Ramda.endsWith specs
💥 Reason for the failure: Rambda method doesn't support arrays
💥 Reason for the failure: Rambda method doesn't support arrays
var R = require('../../../../dist/rambda.js');
var eq = require('./shared/eq');
describe('startsWith', function() {
it('should return true when an array ends with the provided value', function() {
eq(R.endsWith(['c'], ['a', 'b', 'c']), true);
});
it('should return true when an array ends with the provided values', function() {
eq(R.endsWith(['b', 'c'], ['a', 'b', 'c']), true);
});
it('should return false when an array does not end with the provided value', function() {
eq(R.endsWith(['b'], ['a', 'b', 'c']), false);
});
it('should return false when an array does not end with the provided values', function() {
eq(R.endsWith(['a', 'b'], ['a', 'b', 'c']), false);
});
});equals
equals<T>(x: T, y: T): booleanIt deeply compares x and y and returns true if they are equal.
R.equals(
[1, {a:2}, [{b: 3}]],
[1, {a:2}, [{b: 3}]]
) // => trueTry the above R.equals example in Rambda REPL
All Typescript definitions
equals<T>(x: T, y: T): boolean;
equals<T>(x: T): (y: T) => boolean;R.equals source
import { type } from './type'
function parseError(maybeError){
const typeofError = maybeError.__proto__.toString()
if (![ 'Error', 'TypeError' ].includes(typeofError)) return []
return [ typeofError, maybeError.message ]
}
function parseDate(maybeDate){
if (!maybeDate.toDateString) return [ false ]
return [ true, maybeDate.getTime() ]
}
function parseRegex(maybeRegex){
if (maybeRegex.constructor !== RegExp) return [ false ]
return [ true, maybeRegex.toString() ]
}
export function equals(a, b){
if (arguments.length === 1) return _b => equals(a, _b)
const aType = type(a)
if (aType !== type(b)) return false
if ([ 'NaN', 'Undefined', 'Null' ].includes(aType)) return true
if (aType === 'Number'){
if (Object.is(-0, a) !== Object.is(-0, b)) return false
return a.toString() === b.toString()
}
if ([ 'String', 'Boolean' ].includes(aType)){
return a.toString() === b.toString()
}
if (aType === 'Array'){
const aClone = Array.from(a)
const bClone = Array.from(b)
if (aClone.toString() !== bClone.toString()){
return false
}
let loopArrayFlag = true
aClone.forEach((aCloneInstance, aCloneIndex) => {
if (loopArrayFlag){
if (
aCloneInstance !== bClone[ aCloneIndex ] &&
!equals(aCloneInstance, bClone[ aCloneIndex ])
){
loopArrayFlag = false
}
}
})
return loopArrayFlag
}
const aRegex = parseRegex(a)
const bRegex = parseRegex(b)
if (aRegex[ 0 ]){
return bRegex[ 0 ] ? aRegex[ 1 ] === bRegex[ 1 ] : false
} else if (bRegex[ 0 ]) return false
const aDate = parseDate(a)
const bDate = parseDate(b)
if (aDate[ 0 ]){
return bDate[ 0 ] ? aDate[ 1 ] === bDate[ 1 ] : false
} else if (bDate[ 0 ]) return false
const aError = parseError(a)
const bError = parseError(b)
if (aError[ 0 ]){
return bError[ 0 ] ?
aError[ 0 ] === bError[ 0 ] && aError[ 1 ] === bError[ 1 ] :
false
}
if (aType === 'Object'){
const aKeys = Object.keys(a)
if (aKeys.length !== Object.keys(b).length){
return false
}
let loopObjectFlag = true
aKeys.forEach(aKeyInstance => {
if (loopObjectFlag){
const aValue = a[ aKeyInstance ]
const bValue = b[ aKeyInstance ]
if (aValue !== bValue && !equals(aValue, bValue)){
loopObjectFlag = false
}
}
})
return loopObjectFlag
}
return false
}Tests
// import { equals } from 'ramda'
import { equals } from './equals'
test('with array of objects', () => {
const list1 = [ { a : 1 }, [ { b : 2 } ] ]
const list2 = [ { a : 1 }, [ { b : 2 } ] ]
const list3 = [ { a : 1 }, [ { b : 3 } ] ]
expect(equals(list1, list2)).toBeTrue()
expect(equals(list1, list3)).toBeFalse()
})
test('with regex', () => {
expect(equals(/s/, /s/)).toEqual(true)
expect(equals(/s/, /d/)).toEqual(false)
expect(equals(/a/gi, /a/gi)).toEqual(true)
expect(equals(/a/gim, /a/gim)).toEqual(true)
expect(equals(/a/gi, /a/i)).toEqual(false)
})
test('not a number', () => {
expect(equals([ NaN ], [ NaN ])).toBeTrue()
})
test('new number', () => {
expect(equals(new Number(0), new Number(0))).toEqual(true)
expect(equals(new Number(0), new Number(1))).toEqual(false)
expect(equals(new Number(1), new Number(0))).toEqual(false)
})
test('new string', () => {
expect(equals(new String(''), new String(''))).toEqual(true)
expect(equals(new String(''), new String('x'))).toEqual(false)
expect(equals(new String('x'), new String(''))).toEqual(false)
expect(equals(new String('foo'), new String('foo'))).toEqual(true)
expect(equals(new String('foo'), new String('bar'))).toEqual(false)
expect(equals(new String('bar'), new String('foo'))).toEqual(false)
})
test('new Boolean', () => {
expect(equals(new Boolean(true), new Boolean(true))).toEqual(true)
expect(equals(new Boolean(false), new Boolean(false))).toEqual(true)
expect(equals(new Boolean(true), new Boolean(false))).toEqual(false)
expect(equals(new Boolean(false), new Boolean(true))).toEqual(false)
})
test('new Error', () => {
expect(equals(new Error('XXX'), {})).toEqual(false)
expect(equals(new Error('XXX'), new TypeError('XXX'))).toEqual(false)
expect(equals(new Error('XXX'), new Error('YYY'))).toEqual(false)
expect(equals(new Error('XXX'), new Error('XXX'))).toEqual(true)
expect(equals(new Error('XXX'), new TypeError('YYY'))).toEqual(false)
})
test('with dates', () => {
expect(equals(new Date(0), new Date(0))).toEqual(true)
expect(equals(new Date(1), new Date(1))).toEqual(true)
expect(equals(new Date(0), new Date(1))).toEqual(false)
expect(equals(new Date(1), new Date(0))).toEqual(false)
expect(equals(new Date(0), {})).toEqual(false)
expect(equals({}, new Date(0))).toEqual(false)
})
test('ramda spec', () => {
expect(equals({}, {})).toEqual(true)
expect(equals({
a : 1,
b : 2,
},
{
a : 1,
b : 2,
})).toEqual(true)
expect(equals({
a : 2,
b : 3,
},
{
b : 3,
a : 2,
})).toEqual(true)
expect(equals({
a : 2,
b : 3,
},
{
a : 3,
b : 3,
})).toEqual(false)
expect(equals({
a : 2,
b : 3,
c : 1,
},
{
a : 2,
b : 3,
})).toEqual(false)
})
test('works with boolean tuple', () => {
expect(equals([ true, false ], [ true, false ])).toBeTrue()
expect(equals([ true, false ], [ true, true ])).toBeFalse()
})
test('works with equal objects within array', () => {
const objFirst = {
a : {
b : 1,
c : 2,
d : [ 1 ],
},
}
const objSecond = {
a : {
b : 1,
c : 2,
d : [ 1 ],
},
}
const x = [ 1, 2, objFirst, null, '', [] ]
const y = [ 1, 2, objSecond, null, '', [] ]
expect(equals(x, y)).toBeTrue()
})
test('works with different objects within array', () => {
const objFirst = { a : { b : 1 } }
const objSecond = { a : { b : 2 } }
const x = [ 1, 2, objFirst, null, '', [] ]
const y = [ 1, 2, objSecond, null, '', [] ]
expect(equals(x, y)).toBeFalse()
})
test('works with undefined as second argument', () => {
expect(equals(1, undefined)).toBeFalse()
expect(equals(undefined, undefined)).toBeTrue()
})
test('various examples', () => {
expect(equals([ 1, 2, 3 ])([ 1, 2, 3 ])).toBeTrue()
expect(equals([ 1, 2, 3 ], [ 1, 2 ])).toBeFalse()
expect(equals(1, 1)).toBeTrue()
expect(equals(1, '1')).toBeFalse()
expect(equals({}, {})).toBeTrue()
expect(equals({
a : 1,
b : 2,
},
{
b : 2,
a : 1,
})).toBeTrue()
expect(equals({
a : 1,
b : 2,
},
{
a : 1,
b : 1,
})).toBeFalse()
expect(equals({
a : 1,
b : false,
},
{
a : 1,
b : 1,
})).toBeFalse()
expect(equals({
a : 1,
b : 2,
},
{
b : 2,
a : 1,
c : 3,
})).toBeFalse()
expect(equals({
x : {
a : 1,
b : 2,
},
},
{
x : {
b : 2,
a : 1,
c : 3,
},
})).toBeFalse()
expect(equals({
a : 1,
b : 2,
},
{
b : 3,
a : 1,
})).toBeFalse()
expect(equals({ a : { b : { c : 1 } } }, { a : { b : { c : 1 } } })).toBeTrue()
expect(equals({ a : { b : { c : 1 } } }, { a : { b : { c : 2 } } })).toBeFalse()
expect(equals({ a : {} }, { a : {} })).toBeTrue()
expect(equals('', '')).toBeTrue()
expect(equals('foo', 'foo')).toBeTrue()
expect(equals('foo', 'bar')).toBeFalse()
expect(equals(0, false)).toBeFalse()
expect(equals(/\s/g, null)).toBeFalse()
expect(equals(null, null)).toBeTrue()
expect(equals(false)(null)).toBeFalse()
})
test('with custom functions', () => {
function foo(){
return 1
}
foo.prototype.toString = () => ''
const result = equals(foo, foo)
expect(result).toBeFalse()
})
test('with classes', () => {
class Foo{}
const foo = new Foo()
const result = equals(foo, foo)
expect(result).toBeTrue()
})
test('with negative zero', () => {
expect(equals(-0, -0)).toBeTrue()
expect(equals(-0, 0)).toBeFalse()
expect(equals(0, 0)).toBeTrue()
expect(equals(-0, 1)).toBeFalse()
})Typescript test
import {equals} from 'rambda'
describe('R.equals', () => {
it('happy', () => {
const result = equals(4, 1)
result // $ExpectType boolean
})
it('with object', () => {
const foo = {a: 1}
const bar = {a: 2}
const result = equals(foo, bar)
result // $ExpectType boolean
})
it('curried', () => {
const result = equals(4)(1)
result // $ExpectType boolean
})
})14 failed Ramda.equals specs
💥 Reason for the failure: Rambda method doesn't support recursive data structures, objects with same enumerable properties, map/weakmap type of variables | Ramda dispatches to equals method recursively | Rambda method doesn't support equality of functions
💥 Reason for the failure: Rambda method doesn't support recursive data structures, objects with same enumerable properties, map/weakmap type of variables | Ramda dispatches to equals method recursively | Rambda method doesn't support equality of functions
/* global Map, Set, WeakMap, WeakSet */
var R = require('../../../../dist/rambda.js');
var eq = require('./shared/eq');
describe('equals', function() {
var a = [];
var b = a;
it('never considers Boolean primitive equal to Boolean object', function() {
eq(R.equals(true, new Boolean(true)), false);
eq(R.equals(new Boolean(true), true), false);
eq(R.equals(false, new Boolean(false)), false);
eq(R.equals(new Boolean(false), false), false);
});
it('never considers number primitive equal to Number object', function() {
eq(R.equals(0, new Number(0)), false);
eq(R.equals(new Number(0), 0), false);
});
it('never considers string primitive equal to String object', function() {
eq(R.equals('', new String('')), false);
eq(R.equals(new String(''), ''), false);
eq(R.equals('x', new String('x')), false);
eq(R.equals(new String('x'), 'x'), false);
});
var supportsSticky = false;
try { RegExp('', 'y'); supportsSticky = true; } catch (e) {}
var supportsUnicode = false;
try { RegExp('', 'u'); supportsUnicode = true; } catch (e) {}
var listA = [1, 2, 3];
var listB = [1, 3, 2];
var c = {}; c.v = c;
var d = {}; d.v = d;
var e = []; e.push(e);
var f = []; f.push(f);
var nestA = {a:[1, 2, {c:1}], b:1};
var nestB = {a:[1, 2, {c:1}], b:1};
var nestC = {a:[1, 2, {c:2}], b:1};
it('handles recursive data structures', function() {
eq(R.equals(c, d), true);
eq(R.equals(e, f), true);
eq(R.equals(nestA, nestB), true);
eq(R.equals(nestA, nestC), false);
});
it('requires that both objects have the same enumerable properties with the same values', function() {
var a1 = [];
var a2 = [];
a2.x = 0;
var b1 = new Boolean(false);
var b2 = new Boolean(false);
b2.x = 0;
var d1 = new Date(0);
var d2 = new Date(0);
d2.x = 0;
var n1 = new Number(0);
var n2 = new Number(0);
n2.x = 0;
var r1 = /(?:)/;
var r2 = /(?:)/;
r2.x = 0;
var s1 = new String('');
var s2 = new String('');
s2.x = 0;
eq(R.equals(a1, a2), false);
eq(R.equals(b1, b2), false);
eq(R.equals(d1, d2), false);
eq(R.equals(n1, n2), false);
eq(R.equals(r1, r2), false);
eq(R.equals(s1, s2), false);
});
if (typeof ArrayBuffer !== 'undefined' && typeof Int8Array !== 'undefined') {
var typArr1 = new ArrayBuffer(10);
typArr1[0] = 1;
var typArr2 = new ArrayBuffer(10);
typArr2[0] = 1;
var typArr3 = new ArrayBuffer(10);
var intTypArr = new Int8Array(typArr1);
typArr3[0] = 0;
it('handles typed arrays', function() {
eq(R.equals(typArr1, typArr2), true);
eq(R.equals(typArr1, typArr3), false);
eq(R.equals(typArr1, intTypArr), false);
});
}
if (typeof Promise !== 'undefined') {
it('compares Promise objects by identity', function() {
var p = Promise.resolve(42);
var q = Promise.resolve(42);
eq(R.equals(p, p), true);
eq(R.equals(p, q), false);
});
}
if (typeof Map !== 'undefined') {
it('compares Map objects by value', function() {
eq(R.equals(new Map([]), new Map([])), true);
eq(R.equals(new Map([]), new Map([[1, 'a']])), false);
eq(R.equals(new Map([[1, 'a']]), new Map([])), false);
eq(R.equals(new Map([[1, 'a']]), new Map([[1, 'a']])), true);
eq(R.equals(new Map([[1, 'a'], [2, 'b']]), new Map([[2, 'b'], [1, 'a']])), true);
eq(R.equals(new Map([[1, 'a']]), new Map([[2, 'a']])), false);
eq(R.equals(new Map([[1, 'a']]), new Map([[1, 'b']])), false);
eq(R.equals(new Map([[1, 'a'], [2, new Map([[3, 'c']])]]), new Map([[1, 'a'], [2, new Map([[3, 'c']])]])), true);
eq(R.equals(new Map([[1, 'a'], [2, new Map([[3, 'c']])]]), new Map([[1, 'a'], [2, new Map([[3, 'd']])]])), false);
eq(R.equals(new Map([[[1, 2, 3], [4, 5, 6]]]), new Map([[[1, 2, 3], [4, 5, 6]]])), true);
eq(R.equals(new Map([[[1, 2, 3], [4, 5, 6]]]), new Map([[[1, 2, 3], [7, 8, 9]]])), false);
});
it('dispatches to `equals` method recursively in Set', function() {
var a = new Map();
var b = new Map();
a.set(a, a);
eq(R.equals(a, b), false);
a.set(b, b);
b.set(b, b);
b.set(a, a);
eq(R.equals(a, b), true);
});
}
if (typeof Set !== 'undefined') {
it('compares Set objects by value', function() {
eq(R.equals(new Set([]), new Set([])), true);
eq(R.equals(new Set([]), new Set([1])), false);
eq(R.equals(new Set([1]), new Set([])), false);
eq(R.equals(new Set([1, 2]), new Set([2, 1])), true);
eq(R.equals(new Set([1, new Set([2, new Set([3])])]), new Set([1, new Set([2, new Set([3])])])), true);
eq(R.equals(new Set([1, new Set([2, new Set([3])])]), new Set([1, new Set([2, new Set([4])])])), false);
eq(R.equals(new Set([[1, 2, 3], [4, 5, 6]]), new Set([[1, 2, 3], [4, 5, 6]])), true);
eq(R.equals(new Set([[1, 2, 3], [4, 5, 6]]), new Set([[1, 2, 3], [7, 8, 9]])), false);
});
it('dispatches to `equals` method recursively in Set', function() {
var a = new Set();
var b = new Set();
a.add(a);
eq(R.equals(a, b), false);
a.add(b);
b.add(b);
b.add(a);
eq(R.equals(a, b), true);
});
}
if (typeof WeakMap !== 'undefined') {
it('compares WeakMap objects by identity', function() {
var m = new WeakMap([]);
eq(R.equals(m, m), true);
eq(R.equals(m, new WeakMap([])), false);
});
}
if (typeof WeakSet !== 'undefined') {
it('compares WeakSet objects by identity', function() {
var s = new WeakSet([]);
eq(R.equals(s, s), true);
eq(R.equals(s, new WeakSet([])), false);
});
}
it('dispatches to `equals` method recursively', function() {
function Left(x) { this.value = x; }
Left.prototype.equals = function(x) {
return x instanceof Left && R.equals(x.value, this.value);
};
function Right(x) { this.value = x; }
Right.prototype.equals = function(x) {
return x instanceof Right && R.equals(x.value, this.value);
};
eq(R.equals(new Left([42]), new Left([42])), true);
eq(R.equals(new Left([42]), new Left([43])), false);
eq(R.equals(new Left(42), {value: 42}), false);
eq(R.equals({value: 42}, new Left(42)), false);
eq(R.equals(new Left(42), new Right(42)), false);
eq(R.equals(new Right(42), new Left(42)), false);
eq(R.equals([new Left(42)], [new Left(42)]), true);
eq(R.equals([new Left(42)], [new Right(42)]), false);
eq(R.equals([new Right(42)], [new Left(42)]), false);
eq(R.equals([new Right(42)], [new Right(42)]), true);
});
});F
F(): booleanF() // => falseTry the above R.F example in Rambda REPL
All Typescript definitions
F(): boolean;R.F source
export function F(){
return false
}filter
filter<T>(predicate: FilterFunctionArray<T>): (x: T[]) => T[]It filters list or object input with predicate.
const list = [3, 4, 3, 2]
const listPredicate = (x, index) => x - index > 2
const object = {abc: 'fo', xyz: 'bar', baz: 'foo'}
const objectPredicate = (x, prop) => x.length + prop.length > 5
const result = [
R.filter(listPredicate, list),
R.filter(objectPredicate, object)
]
// => [ [3, 4], { xyz: 'bar', baz: 'foo'} ]Try the above R.filter example in Rambda REPL
All Typescript definitions
filter<T>(predicate: FilterFunctionArray<T>): (x: T[]) => T[];
filter<T>(predicate: FilterFunctionArray<T>, x: T[]): T[];
filter<T, U>(predicate: FilterFunctionObject<T>): (x: Dictionary<T>) => Dictionary<T>;
filter<T>(predicate: FilterFunctionObject<T>, x: Dictionary<T>): Dictionary<T>;R.filter source
import { _isArray } from './_internals/_isArray'
function filterObject(fn, obj){
const willReturn = {}
for (const prop in obj){
if (fn(
obj[ prop ], prop, obj
)){
willReturn[ prop ] = obj[ prop ]
}
}
return willReturn
}
export function filter(predicate, list){
if (arguments.length === 1) return _list => filter(predicate, _list)
if (!list) return []
if (!_isArray(list)){
return filterObject(predicate, list)
}
let index = 0
const len = list.length
const willReturn = []
while (index < len){
const value = list[ index ]
if (predicate(value, index)){
willReturn.push(value)
}
index++
}
return willReturn
}Tests
import Ramda from 'ramda'
import { F } from './F'
import { filter } from './filter'
import { T } from './T'
const sampleObject = {
a : 1,
b : 2,
c : 3,
d : 4,
}
test('happy', () => {
const isEven = n => n % 2 === 0
expect(filter(isEven, [ 1, 2, 3, 4 ])).toEqual([ 2, 4 ])
expect(filter(isEven, {
a : 1,
b : 2,
d : 3,
})).toEqual({ b : 2 })
})
test('bad inputs difference between Ramda and Rambda', () => {
expect(filter(T)(undefined)).toEqual([])
expect(filter(F, null)).toEqual([])
expect(() => Ramda.filter(T, null)).toThrowWithMessage(TypeError,
'Cannot read property \'filter\' of null')
expect(() => Ramda.filter(T, undefined)).toThrowWithMessage(TypeError,
'Cannot read property \'filter\' of undefined')
})
test('predicate when input is object', () => {
const obj = {
a : 1,
b : 2,
}
const predicate = (
val, prop, inputObject
) => {
expect(inputObject).toEqual(obj)
expect(typeof prop).toEqual('string')
return val < 2
}
expect(filter(predicate, obj)).toEqual({ a : 1 })
})
test('pass index as second argument', () => {
let counter = 0
filter((x, i) => {
expect(i).toBe(counter)
counter++
},
[ 10, 20, 30 ])
})
test('with object', () => {
const isEven = n => n % 2 === 0
const result = filter(isEven, sampleObject)
const expectedResult = {
b : 2,
d : 4,
}
expect(result).toEqual(expectedResult)
})Typescript test
import {filter} from 'rambda'
const list = [1, 2, 3]
const obj = {a: 1, b: 2}
describe('R.filter with array', () => {
it('happy', () => {
const result = filter<number>(x => {
x // $ExpectType number
return x > 1
}, list)
result // $ExpectType number[]
})
it('curried', () => {
const result = filter<number>(x => {
x // $ExpectType number
return x > 1
})(list)
result // $ExpectType number[]
})
it('pass index as second argument', () => {
filter<number>((x, index) => {
index // $ExpectType number
return x > 1
}, list)
})
})
describe('R.filter with objects', () => {
it('happy', () => {
const result = filter<number>((val, prop, origin) => {
val // $ExpectType number
prop // $ExpectType string
origin // $ExpectType Dictionary<number>
return val > 1
}, obj)
result // $ExpectType Dictionary<number>
})
it('curried version requires second dummy type', () => {
const result = filter<number, any>((val, prop, origin) => {
val // $ExpectType number
prop // $ExpectType string
origin // $ExpectType Dictionary<number>
return val > 1
})(obj)
result // $ExpectType Dictionary<number>
})
})1 failed Ramda.filter specs
💥 Reason for the failure: Ramda method dispatches to filter method of object
💥 Reason for the failure: Ramda method dispatches to filter method of object
var R = require('../../../../dist/rambda.js');
var eq = require('./shared/eq');
var Maybe = require('./shared/Maybe');
describe('filter', function() {
var even = function(x) {return x % 2 === 0;};
it('dispatches to passed-in non-Array object with a `filter` method', function() {
var f = {filter: function(f) { return f('called f.filter'); }};
eq(R.filter(function(s) { return s; }, f), 'called f.filter');
});
it('correctly uses fantasy-land implementations', function() {
var m1 = Maybe.Just(-1);
var m2 = R.filter(function(x) { return x > 0; } , m1);
eq(m2.isNothing, true);
});
});find
find<T>(predicate: (x: T) => boolean, list: ReadonlyArray<T>): T | undefinedIt returns the first element of list that satisfy the predicate.
If there is no such element, it returns undefined.
const predicate = x => R.type(x.foo) === 'Number'
const list = [{foo: 'bar'}, {foo: 1}]
const result = R.find(predicate, list)
// => {foo: 1}Try the above R.find example in Rambda REPL
All Typescript definitions
find<T>(predicate: (x: T) => boolean, list: ReadonlyArray<T>): T | undefined;
find<T>(predicate: (x: T, index: number) => boolean, list: ReadonlyArray<T>): T | undefined;
find<T>(predicate: (x: T) => boolean): (list: ReadonlyArray<T>) => T | undefined;
find<T>(predicate: (x: T, index: number) => boolean): (list: ReadonlyArray<T>) => T | undefined;R.find source
export function find(predicate, list){
if (arguments.length === 1) return _list => find(predicate, _list)
let index = 0
const len = list.length
while (index < len){
const x = list[ index ]
if (predicate(x, index)){
return x
}
index++
}
}Tests
import { find } from './find'
import { propEq } from './propEq'
const list = [ { a : 1 }, { a : 2 }, { a : 3 } ]
test('happy', () => {
const fn = propEq('a', 2)
expect(find(fn, list)).toEqual({ a : 2 })
})
test('with curry', () => {
const fn = propEq('a', 4)
expect(find(fn)(list)).toBeUndefined()
})
test('with empty list', () => {
expect(find(() => true, [])).toBeUndefined()
})
test('pass index', () => {
find((_, i) => {
expect(i).toBe(0)
},
[ 'foo' ])
})Typescript test
import {find} from 'rambda'
const list = [1, 2, 3]
describe('R.find', () => {
it('happy', () => {
const predicate = (x: number) => x > 2
const result = find(predicate, list)
result // $ExpectType number | undefined
})
it('curried', () => {
const predicate = (x: number) => x > 2
const result = find(predicate)(list)
result // $ExpectType number | undefined
})
it('pass index as second argument', () => {
const predicate = (x: number, index: number) => {
index // $ExpectType number
return x > 2
}
const result = find(predicate, list)
result // $ExpectType number | undefined
})
it('pass index as second argument | curried', () => {
const predicate = (x: number, index: number) => {
index // $ExpectType number
return x > 2
}
const result = find(predicate)(list)
result // $ExpectType number | undefined
})
})findIndex
findIndex<T>(predicate: (x: T) => boolean, list: ReadonlyArray<T>): numberIt returns the index of the first element of list satisfying the predicate function.
If there is no such element, then -1 is returned.
const predicate = x => R.type(x.foo) === 'Number'
const list = [{foo: 'bar'}, {foo: 1}]
const result = R.findIndex(predicate, list)
// => 1Try the above R.findIndex example in Rambda REPL
All Typescript definitions
findIndex<T>(predicate: (x: T) => boolean, list: ReadonlyArray<T>): number;
findIndex<T>(predicate: (x: T, index: number) => boolean, list: ReadonlyArray<T>): number;
findIndex<T>(predicate: (x: T) => boolean): (list: ReadonlyArray<T>) => number;
findIndex<T>(predicate: (x: T, index: number) => boolean): (list: ReadonlyArray<T>) => number;R.findIndex source
export function findIndex(predicate, list){
if (arguments.length === 1) return _list => findIndex(predicate, _list)
const len = list.length
let index = -1
while (++index < len){
if (predicate(list[ index ], index)){
return index
}
}
return -1
}Tests
import { findIndex } from './findIndex'
import { propEq } from './propEq'
test('happy', () => {
expect(findIndex(propEq('a', 2))([ { a : 1 }, { a : 2 }, { a : 3 } ])).toEqual(1)
expect(findIndex(propEq('a', 1))([ { a : 1 }, { a : 2 }, { a : 3 } ])).toEqual(0)
expect(findIndex(propEq('a', 4))([ { a : 1 }, { a : 2 }, { a : 3 } ])).toEqual(-1)
})
test('pass index as second argument', () => {
findIndex((x, i) => {
expect(typeof x).toBe('number')
expect(typeof i).toBe('number')
})([ 10, 12, 15 ])
})Typescript test
import {findIndex} from 'rambda'
const list = [1, 2, 3]
describe('R.findIndex', () => {
it('happy', () => {
const predicate = (x: number) => x > 2
const result = findIndex(predicate, list)
result // $ExpectType number
})
it('curried', () => {
const predicate = (x: number) => x > 2
const result = findIndex(predicate)(list)
result // $ExpectType number
})
it('pass index as second argument', () => {
const predicate = (x: number, index: number) => {
index // $ExpectType number
return x > 2
}
const result = findIndex(predicate, list)
result // $ExpectType number
})
it('pass index as second argument | curried', () => {
const predicate = (x: number, index: number) => {
index // $ExpectType number
return x > 2
}
const result = findIndex(predicate)(list)
result // $ExpectType number
})
})findLast
findLast<T>(fn: (x: T) => boolean, list: T[]): T | undefinedIt returns the last element of list satisfying the predicate function.
If there is no such element, then undefined is returned.
const predicate = x => R.type(x.foo) === 'Number'
const list = [{foo: 0}, {foo: 1}]
const result = R.findLast(predicate, list)
// => {foo: 1}Try the above R.findLast example in Rambda REPL
All Typescript definitions
findLast<T>(fn: (x: T) => boolean, list: T[]): T | undefined;
findLast<T>(fn: (x: T, index: number) => boolean, list: T[]): T | undefined;
findLast<T>(fn: (x: T) => boolean): (list: T[]) => T | undefined;
findLast<T>(fn: (x: T, index: number) => boolean): (list: T[]) => T | undefined;R.findLast source
export function findLast(predicate, list){
if (arguments.length === 1) return _list => findLast(predicate, _list)
let index = list.length
while (--index >= 0){
if (predicate(list[ index ], index)){
return list[ index ]
}
}
return undefined
}Tests
import { findLast } from './findLast'
test('happy', () => {
const result = findLast((x, i) => {
expect(typeof i).toBe('number')
return x > 1
},
[ 1, 1, 1, 2, 3, 4, 1 ])
expect(result).toEqual(4)
expect(findLast(x => x === 0, [ 0, 1, 1, 2, 3, 4, 1 ])).toEqual(0)
})
test('with curry', () => {
expect(findLast(x => x > 1)([ 1, 1, 1, 2, 3, 4, 1 ])).toEqual(4)
})
const obj1 = { x : 100 }
const obj2 = { x : 200 }
const a = [ 11, 10, 9, 'cow', obj1, 8, 7, 100, 200, 300, obj2, 4, 3, 2, 1, 0 ]
const even = function (x){
return x % 2 === 0
}
const gt100 = function (x){
return x > 100
}
const isStr = function (x){
return typeof x === 'string'
}
const xGt100 = function (o){
return o && o.x > 100
}
test('ramda 1', () => {
expect(findLast(even, a)).toEqual(0)
expect(findLast(gt100, a)).toEqual(300)
expect(findLast(isStr, a)).toEqual('cow')
expect(findLast(xGt100, a)).toEqual(obj2)
})
test('ramda 2', () => {
expect(findLast(even, [ 'zing' ])).toEqual(undefined)
})
test('ramda 3', () => {
expect(findLast(even, [ 2, 3, 5 ])).toEqual(2)
})
test('ramda 4', () => {
expect(findLast(even, [])).toEqual(undefined)
})Typescript test
import {findLast} from 'rambda'
const list = [1, 2, 3]
describe('R.findLast', () => {
it('happy', () => {
const predicate = (x: number) => x > 2
const result = findLast(predicate, list)
result // $ExpectType number | undefined
})
it('curried', () => {
const predicate = (x: number) => x > 2
const result = findLast(predicate)(list)
result // $ExpectType number | undefined
})
it('pass index as second argument', () => {
const predicate = (x: number, index: number) => {
index // $ExpectType number
return x > 2
}
const result = findLast(predicate, list)
result // $ExpectType number | undefined
})
it('pass index as second argument | curried', () => {
const predicate = (x: number, index: number) => {
index // $ExpectType number
return x > 2
}
const result = findLast(predicate)(list)
result // $ExpectType number | undefined
})
})findLastIndex
findLastIndex<T>(predicate: (x: T) => boolean, list: T[]): numberIt returns the index of the last element of list satisfying the predicate function.
If there is no such element, then -1 is returned.
const predicate = x => R.type(x.foo) === 'Number'
const list = [{foo: 0}, {foo: 1}]
const result = R.findLastIndex(predicate, list)
// => 1Try the above R.findLastIndex example in Rambda REPL
All Typescript definitions
findLastIndex<T>(predicate: (x: T) => boolean, list: T[]): number;
findLastIndex<T>(predicate: (x: T, index: number) => boolean, list: T[]): number;
findLastIndex<T>(predicate: (x: T) => boolean): (list: T[]) => number;
findLastIndex<T>(predicate: (x: T, index: number) => boolean): (list: T[]) => number;R.findLastIndex source
export function findLastIndex(fn, list){
if (arguments.length === 1) return _list => findLastIndex(fn, _list)
let index = list.length
while (--index >= 0){
if (fn(list[ index ], index)){
return index
}
}
return -1
}Tests
import { findLastIndex } from './findLastIndex'
test('happy', () => {
const result = findLastIndex((x, i) => {
expect(typeof i).toBe('number')
return x > 1
},
[ 1, 1, 1, 2, 3, 4, 1 ])
expect(result).toEqual(5)
expect(findLastIndex(x => x === 0, [ 0, 1, 1, 2, 3, 4, 1 ])).toEqual(0)
})
test('with curry', () => {
expect(findLastIndex(x => x > 1)([ 1, 1, 1, 2, 3, 4, 1 ])).toEqual(5)
})
const obj1 = { x : 100 }
const obj2 = { x : 200 }
const a = [ 11, 10, 9, 'cow', obj1, 8, 7, 100, 200, 300, obj2, 4, 3, 2, 1, 0 ]
const even = function (x){
return x % 2 === 0
}
const gt100 = function (x){
return x > 100
}
const isStr = function (x){
return typeof x === 'string'
}
const xGt100 = function (o){
return o && o.x > 100
}
test('ramda 1', () => {
expect(findLastIndex(even, a)).toEqual(15)
expect(findLastIndex(gt100, a)).toEqual(9)
expect(findLastIndex(isStr, a)).toEqual(3)
expect(findLastIndex(xGt100, a)).toEqual(10)
})
test('ramda 2', () => {
expect(findLastIndex(even, [ 'zing' ])).toEqual(-1)
})
test('ramda 3', () => {
expect(findLastIndex(even, [ 2, 3, 5 ])).toEqual(0)
})
test('ramda 4', () => {
expect(findLastIndex(even, [])).toEqual(-1)
})Typescript test
import {findLastIndex} from 'rambda'
const list = [1, 2, 3]
describe('R.findLastIndex', () => {
it('happy', () => {
const predicate = (x: number) => x > 2
const result = findLastIndex(predicate, list)
result // $ExpectType number
})
it('curried', () => {
const predicate = (x: number) => x > 2
const result = findLastIndex(predicate)(list)
result // $ExpectType number
})
it('pass index as second argument', () => {
const predicate = (x: number, index: number) => {
index // $ExpectType number
return x > 2
}
const result = findLastIndex(predicate, list)
result // $ExpectType number
})
it('pass index as second argument | curried', () => {
const predicate = (x: number, index: number) => {
index // $ExpectType number
return x > 2
}
const result = findLastIndex(predicate)(list)
result // $ExpectType number
})
})flatten
flatten<T>(list: ReadonlyArray<any>): T[]It deeply flattens an array.
const result = R.flatten([
1,
2,
[3, 30, [300]],
[4]
])
// => [ 1, 2, 3, 30, 300, 4 ]Try the above R.flatten example in Rambda REPL
All Typescript definitions
flatten<T>(list: ReadonlyArray<any>): T[];R.flatten source
import { _isArray } from './_internals/_isArray'
export function flatten(list, input){
const willReturn = input === undefined ? [] : input
for (let i = 0; i < list.length; i++){
if (_isArray(list[ i ])){
flatten(list[ i ], willReturn)
} else {
willReturn.push(list[ i ])
}
}
return willReturn
}Tests
import { flatten } from './flatten'
test('happy', () => {
expect(flatten([ 1, 2, 3, [ [ [ [ [ 4 ] ] ] ] ] ])).toEqual([ 1, 2, 3, 4 ])
expect(flatten([ 1, [ 2, [ [ 3 ] ] ], [ 4 ] ])).toEqual([ 1, 2, 3, 4 ])
expect(flatten([ 1, [ 2, [ [ [ 3 ] ] ] ], [ 4 ] ])).toEqual([ 1, 2, 3, 4 ])
expect(flatten([ 1, 2, [ 3, 4 ], 5, [ 6, [ 7, 8, [ 9, [ 10, 11 ], 12 ] ] ] ])).toEqual([ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 ])
})
test('readme example', () => {
const result = flatten([ 1, 2, [ 3, 30, [ 300 ] ], [ 4 ] ])
expect(result).toEqual([ 1, 2, 3, 30, 300, 4 ])
})Typescript test
import {flatten} from 'rambda'
describe('flatten', () => {
it('happy', () => {
const result = flatten<number>([1, 2, [3, [4]]])
result // $ExpectType number[]
})
})flip
flip<T, U, TResult>(fn: (arg0: T, arg1: U) => TResult): (arg1: U, arg0?: T) => TResultIt returns function which calls fn with exchanged first and second argument.
const subtractFlip = R.flip(R.subtract)
const result = [
subtractFlip(1,7),
R.flip(1, 6)
]
// => [6, -6]Try the above R.flip example in Rambda REPL
All Typescript definitions
flip<T, U, TResult>(fn: (arg0: T, arg1: U) => TResult): (arg1: U, arg0?: T) => TResult;
flip<F extends (...args: any) => any, P extends FunctionToolbelt.Parameters<F>>(fn: F): FunctionToolbelt.Curry<(...args: ListToolbelt.Merge<[P[1], P[0]], P>) => FunctionToolbelt.Return<F>>;R.flip source
function flipFn(fn){
return (...input) => {
if (input.length === 1){
return holder => fn(holder, input[ 0 ])
} else if (input.length === 2){
return fn(input[ 1 ], input[ 0 ])
} else if (input.length === 3){
return fn(
input[ 1 ], input[ 0 ], input[ 2 ]
)
} else if (input.length === 4){
return fn(
input[ 1 ], input[ 0 ], input[ 2 ], input[ 3 ]
)
}
throw new Error('R.flip doesn\'t work with arity > 4')
}
}
export function flip(fn){
return flipFn(fn)
}Tests
import { flip } from './flip'
import { subtract } from './subtract'
import { update } from './update'
test('function with arity of 2', () => {
const subtractFlipped = flip(subtract)
expect(subtractFlipped(1)(7)).toEqual(6)
expect(subtractFlipped(1, 7)).toEqual(6)
expect(subtractFlipped(
1, 7, 9
)).toEqual(6)
})
test('function with arity of 3', () => {
const updateFlipped = flip(update)
const result = updateFlipped(
88, 0, [ 1, 2, 3 ]
)
const curriedResult = updateFlipped(88, 0)([ 1, 2, 3 ])
const tripleCurriedResult = updateFlipped(88)(0)([ 1, 2, 3 ])
expect(result).toEqual([ 88, 2, 3 ])
expect(curriedResult).toEqual([ 88, 2, 3 ])
expect(tripleCurriedResult).toEqual([ 88, 2, 3 ])
})
test('function with arity of 4', () => {
const testFunction = (
a, b, c, d
) => `${ a - b }==${ c - d }`
const testFunctionFlipped = flip(testFunction)
const result = testFunction(
1, 2, 3, 4
)
const flippedResult = testFunctionFlipped(
2, 1, 3, 4
)
expect(result).toEqual(flippedResult)
expect(result).toEqual('-1==-1')
})
test('function with arity of 5', () => {
const testFunction = (
a, b, c, d, e
) => `${ a - b }==${ c - d - e }`
const testFunctionFlipped = flip(testFunction)
expect(() => testFunctionFlipped(
1, 2, 3, 4, 5
)).toThrowWithMessage(Error,
'R.flip doesn\'t work with arity > 4')
})Typescript test
import * as R from 'ramda'
import {flip, subtract} from 'rambda'
describe('R.flip', () => {
it('function with arity of 2', () => {
const subtractFlipped = flip(subtract)
const result = subtractFlipped(1, 7)
const curriedResult = subtractFlipped(1)(7)
curriedResult // $ExpectType number
// This is wrong
// ============================================
result // $ExpectType (y: number) => number
})
it('function with arity of 3', () => {
function testFunction(a: number, b: string, c: number): string {
return `${b}==${a + c}`
}
const flippedTestFunction = flip(testFunction)
const result = flippedTestFunction('foo', 1, 2)
result // $ExpectType string
})
})
describe('Ramda.flip', () => {
it('function with arity of 2', () => {
const subtractFlipped = R.flip(R.subtract)
const result = subtractFlipped(1, 7)
const curriedResult = subtractFlipped(1)(7)
curriedResult // $ExpectType number
// This is wrong
// ============================================
result // $ExpectType (b: number) => number
})
})4 failed Ramda.flip specs
💥 Reason for the failure: Ramda.flip returns a curried function | Rambda.flip work only for functions with arity below 5
💥 Reason for the failure: Ramda.flip returns a curried function | Rambda.flip work only for functions with arity below 5
var jsv = require('jsverify');
var R = require('../../../../dist/rambda.js');
var eq = require('./shared/eq');
var funcN = require('./shared/funcN');
describe('flip', function() {
it('returns a function which inverts the first two arguments to the supplied function', function() {
var f = function(a, b, c) {return a + ' ' + b + ' ' + c;};
var g = R.flip(f);
eq(f('a', 'b', 'c'), 'a b c');
eq(g('a', 'b', 'c'), 'b a c');
});
it('returns a curried function', function() {
var f = function(a, b, c) {return a + ' ' + b + ' ' + c;};
var g = R.flip(f)('a');
eq(g('b', 'c'), 'b a c');
});
it('returns a function with the correct arity', function() {
var f2 = function(a, b) {return a + ' ' + b;};
var f3 = function(a, b, c) {return a + ' ' + b + ' ' + c;};
eq(R.flip(f2).length, 2);
eq(R.flip(f3).length, 3);
});
});
describe('flip properties', function() {
jsv.property('inverts first two arguments', funcN(3), jsv.json, jsv.json, jsv.json, function(f, a, b, c) {
var g = R.flip(f);
return R.equals(f(a, b, c), g(b, a, c));
});
});forEach
forEach<T, U>(fn: MapFunctionObject<T, U>, list: Dictionary<T>): Dictionary<T>It applies iterable function over all members of list and returns list.
const sideEffect = {}
const result = R.forEach(
x => sideEffect[`foo${x}`] = x
)([1, 2])
sideEffect //=> {foo1: 1, foo2: 2}
result //=> [1, 2]Try the above R.forEach example in Rambda REPL
All Typescript definitions
forEach<T, U>(fn: MapFunctionObject<T, U>, list: Dictionary<T>): Dictionary<T>;
forEach<T, U>(fn: MapFunctionArray<T, U>, list: T[]): T[];
forEach<T, U>(fn: MapFunctionArray<T, U>): (list: T[]) => T[];
forEach<T, U, S>(fn: MapFunctionObject<T, U>): (list: Dictionary<T>) => Dictionary<T>;
forEach<T>(fn: MapFunctionArray<T, T>): (list: T[]) => T[];
forEach<T>(fn: MapFunctionArray<T, T>, list: ReadonlyArray<T>): T[];R.forEach source
import { _isArray } from './_internals/_isArray'
import { _keys } from './_internals/_keys'
export function forEach(fn, list){
if (arguments.length === 1) return _list => forEach(fn, _list)
if (list === undefined){
return
}
if (_isArray(list)){
let index = 0
const len = list.length
while (index < len){
fn(
list[ index ], index, list
)
index++
}
} else {
let index = 0
const keys = _keys(list)
const len = keys.length
while (index < len){
const key = keys[ index ]
fn(
list[ key ], key, list
)
index++
}
}
return list
}Tests
import { forEach } from './forEach'
import { type } from './type'
test('iterate over object', () => {
const obj = {
a : 1,
b : [ 1, 2 ],
c : { d : 7 },
f : 'foo',
}
const result = {}
const returned = forEach((
val, prop, inputObj
) => {
expect(type(inputObj)).toBe('Object')
result[ prop ] = `${ prop }-${ type(val) }`
})(obj)
const expected = {
a : 'a-Number',
b : 'b-Array',
c : 'c-Object',
f : 'f-String',
}
expect(result).toEqual(expected)
expect(returned).toEqual(obj)
})
test('happy', () => {
const sideEffect = {}
forEach(x => sideEffect[ `foo${ x }` ] = x + 10)([ 1, 2 ])
expect(sideEffect).toEqual({
foo1 : 11,
foo2 : 12,
})
})
test('happy 2', () => {
const list = [
{
x : 1,
y : 2,
},
{
x : 100,
y : 200,
},
{
x : 300,
y : 400,
},
{
x : 234,
y : 345,
},
]
const sideEffect = {}
const result = forEach(elem => {
sideEffect[ elem.x ] = elem.y
}, list)
const expectedSideEffect = {
1 : 2,
100 : 200,
300 : 400,
234 : 345,
}
expect(sideEffect).toEqual(expectedSideEffect)
expect(result).toEqual(list)
})
test('with empty list', () => {
const list = []
const result = forEach(x => x * x)(list)
expect(result).toEqual(list)
})
test('with wrong input', () => {
const list = undefined
const result = forEach(x => x * x)(list)
expect(result).toBeUndefined()
})
test('returns the input', () => {
const list = [ 1, 2, 3 ]
const result = forEach(x => x * x)(list)
expect(result).toEqual(list)
})
test('pass index as second argument', () => {
const list = [ 11, 21, 31 ]
const indexes = []
const result = forEach((x, i) => indexes.push(i))(list)
expect(indexes).toEqual([ 0, 1, 2 ])
})Typescript test
import {forEach} from 'rambda'
describe('R.forEach with arrays', () => {
it('iterable returns the same type as the input', () => {
const result = forEach<number>(
(a, b) => {
a // $ExpectType number
b // $ExpectType number
return a + 2
},
[1, 2, 3]
)
result // $ExpectType number[]
})
it('iterable returns the same type as the input - curried', () => {
const result = forEach<number>((a, b) => {
a // $ExpectType number
b // $ExpectType number
return a + 2
})([1, 2, 3])
result // $ExpectType number[]
})
it('iterable with index argument', () => {
const result = forEach<number, string>(
(a, b) => {
a // $ExpectType number
b // $ExpectType number
return `${a}`
},
[1, 2, 3]
)
result // $ExpectType number[]
})
it('iterable with index argument - curried', () => {
const result = forEach<number, string>((a, b) => {
a // $ExpectType number
b // $ExpectType number
return `${a}`
})([1, 2, 3])
result // $ExpectType number[]
})
})
describe('R.forEach with objects', () => {
it('iterable with all three arguments - curried', () => {
// It requires dummy third typing argument
// in order to distinguish compared to curry typings for arrays
// ============================================
const result = forEach<number, string, any>((a, b, c) => {
a // $ExpectType number
b // $ExpectType string
c // $ExpectType Dictionary<number>
return `${a}`
})({a: 1, b: 2})
result // $ExpectType Dictionary<number>
})
it('iterable with all three arguments', () => {
const result = forEach<number, string>(
(a, b, c) => {
a // $ExpectType number
b // $ExpectType string
c // $ExpectType Dictionary<number>
return `${a}`
},
{a: 1, b: 2}
)
result // $ExpectType Dictionary<number>
})
it('iterable with property argument', () => {
const result = forEach<number, string>(
(a, b) => {
a // $ExpectType number
b // $ExpectType string
return `${a}`
},
{a: 1, b: 2}
)
result // $ExpectType Dictionary<number>
})
it('iterable with no property argument', () => {
const result = forEach<number, string>(
a => {
a // $ExpectType number
return `${a}`
},
{a: 1, b: 2}
)
result // $ExpectType Dictionary<number>
})
})1 failed Ramda.forEach specs
💥 Reason for the failure: Ramda method dispatches to forEach method
💥 Reason for the failure: Ramda method dispatches to forEach method
var R = require('../../../../dist/rambda.js');
var eq = require('./shared/eq');
describe('forEach', function() {
var list = [{x: 1, y: 2}, {x: 100, y: 200}, {x: 300, y: 400}, {x: 234, y: 345}];
it('dispatches to `forEach` method', function() {
var dispatched = false;
var fn = function() {};
function DummyList() {}
DummyList.prototype.forEach = function(callback) {
dispatched = true;
eq(callback, fn);
};
R.forEach(fn, new DummyList());
eq(dispatched, true);
});
});fromPairs
fromPairs<V>(listOfPairs: KeyValuePair<string, V>[]): { [index: string]: V }It transforms a listOfPairs to an object.
const listOfPairs = [ [ 'a', 1 ], [ 'b', 2 ], [ 'c', [ 3, 4 ] ] ]
const expected = {
a : 1,
b : 2,
c : [ 3, 4 ],
}
const result = R.fromPairs(listOfPairs)
// => `result` is equal to `expected`Try the above R.fromPairs example in Rambda REPL
All Typescript definitions
fromPairs<V>(listOfPairs: KeyValuePair<string, V>[]): { [index: string]: V };
fromPairs<V>(listOfPairs: KeyValuePair<number, V>[]): { [index: number]: V };R.fromPairs source
export function fromPairs(listOfPairs){
const toReturn = {}
listOfPairs.forEach(([ prop, value ]) => toReturn[ prop ] = value)
return toReturn
}Tests
import { fromPairs } from './fromPairs'
const list = [
[ 'a', 1 ],
[ 'b', 2 ],
[ 'c', [ 3, 4 ] ],
]
const expected = {
a : 1,
b : 2,
c : [ 3, 4 ],
}
test('happy', () => {
expect(fromPairs(list)).toEqual(expected)
})Typescript test
import {fromPairs} from 'rambda'
describe('R.fromPairs - require explicit type for input list', () => {
it('with string index', () => {
const list: [string, number][] = [
['a', 1],
['b', 2],
['c', 3],
]
const result = fromPairs(list)
result // $ExpectType { [index: string]: number; }
})
it('with number index', () => {
const list: [number, string][] = [
[10, 'foo'],
[20, 'bar'],
[30, 'baz'],
]
const result = fromPairs(list)
result // $ExpectType { [index: number]: string; }
})
})groupBy
groupBy<T>(groupFn: (x: T) => string, list: ReadonlyArray<T>): { [index: string]: T[] }It splits list according to a provided groupFn function and returns an object.
const list = [ 'a', 'b', 'aa', 'bb' ]
const groupFn = x => x.length
const result = R.groupBy(groupFn, list)
// => { '1': ['a', 'b'], '2': ['aa', 'bb'] }Try the above R.groupBy example in Rambda REPL
All Typescript definitions
groupBy<T>(groupFn: (x: T) => string, list: ReadonlyArray<T>): { [index: string]: T[] };
groupBy<T>(groupFn: (x: T) => string): (list: ReadonlyArray<T>) => { [index: string]: T[] };R.groupBy source
export function groupBy(groupFn, list){
if (arguments.length === 1) return _list => groupBy(groupFn, _list)
const result = {}
for (let i = 0; i < list.length; i++){
const item = list[ i ]
const key = groupFn(item)
if (!result[ key ]){
result[ key ] = []
}
result[ key ].push(item)
}
return result
}Tests
import { groupBy } from './groupBy'
import { prop } from './prop'
test('groupBy', () => {
const list = [
{
age : 12,
name : 'john',
},
{
age : 12,
name : 'jack',
},
{
age : 24,
name : 'mary',
},
{
age : 24,
name : 'steve',
},
]
const expectedResult = {
12 : [
{
age : 12,
name : 'john',
},
{
age : 12,
name : 'jack',
},
],
24 : [
{
age : 24,
name : 'mary',
},
{
age : 24,
name : 'steve',
},
],
}
expect(groupBy(prop('age'))(list)).toEqual(expectedResult)
expect(groupBy(prop('age'), list)).toEqual(expectedResult)
})Typescript test
import {groupBy} from 'rambda'
describe('R.groupBy', () => {
it('happy', () => {
const groupByFn = (x: string) => String(x.length)
const list = ['foo', 'barr', 'bazzz']
const result = groupBy(groupByFn, list)
result // $ExpectType { [index: string]: string[]; }
const curriedResult = groupBy(groupByFn)(list)
curriedResult // $ExpectType { [index: string]: string[]; }
})
})1 failed Ramda.groupBy specs
💥 Reason for the failure: Ramda method support transforms
💥 Reason for the failure: Ramda method support transforms
var R = require('../../../../dist/rambda.js');
var eq = require('./shared/eq');
var _isTransformer = require('rambda/internal/_isTransformer');
describe('groupBy', function() {
it('dispatches on transformer objects in list position', function() {
var byType = R.prop('type');
var xf = {
'@@transducer/init': function() { return {}; },
'@@transducer/result': function(x) { return x; },
'@@transducer/step': R.mergeRight
};
eq(_isTransformer(R.groupBy(byType, xf)), true);
});
});groupWith
groupWith<T>(compareFn: (x: T, y: T) => boolean): (list: ReadonlyArray<T>) => T[][]It returns separated version of list, where separation is done with equality compareFn function.
const compareFn = (x, y) => x === y
const list = [1, 2, 2, 1, 1, 2]
const result = R.groupWith(isConsecutive, list)
// => [[1], [2,2], [1,1], [2]]Try the above R.groupWith example in Rambda REPL
All Typescript definitions
groupWith<T>(compareFn: (x: T, y: T) => boolean): (list: ReadonlyArray<T>) => T[][];
groupWith<T>(compareFn: (x: T, y: T) => boolean, list: ReadonlyArray<T>): T[][];
groupWith<T>(compareFn: (x: T, y: T) => boolean, list: string): string[];R.groupWith source
import { _isArray } from './_internals/_isArray'
export function groupWith(compareFn, list){
if (!_isArray(list)) throw new TypeError('list.reduce is not a function')
const clone = list.slice()
if (list.length === 1) return [ clone ]
const toReturn = []
let holder = []
clone.reduce((
prev, current, i
) => {
if (i === 0) return current
const okCompare = compareFn(prev, current)
const holderIsEmpty = holder.length === 0
const lastCall = i === list.length - 1
if (okCompare){
if (holderIsEmpty) holder.push(prev)
holder.push(current)
if (lastCall) toReturn.push(holder)
return current
}
if (holderIsEmpty){
toReturn.push([ prev ])
if (lastCall) toReturn.push([ current ])
return current
}
toReturn.push(holder)
if (lastCall) toReturn.push([ current ])
holder = []
return current
}, undefined)
return toReturn
}Tests
import { equals } from './equals'
import { groupWith } from './groupWith'
test('issue is fixed', () => {
const result = groupWith(equals, [ 1, 2, 2, 3 ])
const expected = [ [ 1 ], [ 2, 2 ], [ 3 ] ]
expect(result).toEqual(expected)
})
test('long list', () => {
const result = groupWith(equals, [
0,
1,
1,
2,
3,
5,
8,
13,
21,
21,
21,
1,
2,
])
const expected = [
[ 0 ],
[ 1, 1 ],
[ 2 ],
[ 3 ],
[ 5 ],
[ 8 ],
[ 13 ],
[ 21, 21, 21 ],
[ 1 ],
[ 2 ],
]
expect(result).toEqual(expected)
})
test('readme example', () => {
const list = [ 4, 3, 6, 2, 2, 1 ]
const result = groupWith((a, b) => a - b === 1, list)
const expected = [ [ 4, 3 ], [ 6 ], [ 2 ], [ 2, 1 ] ]
expect(result).toEqual(expected)
})
test('throw with string as input', () => {
expect(() => groupWith(equals, 'Mississippi')).toThrowWithMessage(TypeError,
'list.reduce is not a function')
})
const isConsecutive = function (a, b){
return a + 1 === b
}
test('fix coverage', () => {
expect(groupWith(isConsecutive, [ 1, 2, 3, 0 ])).toEqual([ [ 1, 2, 3 ], [ 0 ] ])
})
test('from ramda 0', () => {
expect(groupWith(equals, [])).toEqual([])
expect(groupWith(isConsecutive, [])).toEqual([])
})
test('from ramda 1', () => {
expect(groupWith(isConsecutive, [ 4, 3, 2, 1 ])).toEqual([
[ 4 ],
[ 3 ],
[ 2 ],
[ 1 ],
])
})
test('from ramda 2', () => {
expect(groupWith(isConsecutive, [ 1, 2, 3, 4 ])).toEqual([ [ 1, 2, 3, 4 ] ])
})
test('from ramda 3', () => {
expect(groupWith(isConsecutive, [ 1, 2, 2, 3 ])).toEqual([
[ 1, 2 ],
[ 2, 3 ],
])
expect(groupWith(isConsecutive, [ 1, 2, 9, 3, 4 ])).toEqual([
[ 1, 2 ],
[ 9 ],
[ 3, 4 ],
])
})
test('list with single item', () => {
const result = groupWith(equals, [ 0 ])
const expected = [ [ 0 ] ]
expect(result).toEqual(expected)
})Typescript test
import {groupWith} from 'rambda'
describe('R.groupWith', () => {
it('happy', () => {
const groupWithFn = (x: string, y: string) => x.length === y.length
const list = ['foo', 'bar', 'bazzz']
const result = groupWith(groupWithFn, list)
const curriedResult = groupWith(groupWithFn)(list)
result // $ExpectType string[][]
curriedResult // $ExpectType string[][]
})
})2 failed Ramda.groupWith specs
💥 Reason for the failure: Ramda method support string
💥 Reason for the failure: Ramda method support string
var R = require('../../../../dist/rambda.js');
var eq = require('./shared/eq');
describe('groupWith', function() {
it('can be turned into the original list through concatenation', function() {
var list = [1, 1, 2, 3, 4, 4, 5, 5];
eq(R.unnest(R.groupWith(R.equals, list)), list);
eq(R.unnest(R.groupWith(R.complement(R.equals), list)), list);
eq(R.unnest(R.groupWith(R.T, list)), list);
eq(R.unnest(R.groupWith(R.F, list)), list);
});
it('also works on strings', function() {
eq(R.groupWith(R.equals)('Mississippi'), ['M','i','ss','i','ss','i','pp','i']);
});
});has
has<T>(prop: string, obj: T): booleanIt returns true if obj has property prop.
const obj = {a: 1}
const result = [
R.has('a', obj),
R.has('b', obj)
]
// => [true, false]Try the above R.has example in Rambda REPL
All Typescript definitions
has<T>(prop: string, obj: T): boolean;
has(prop: string): <T>(obj: T) => boolean;R.has source
export function has(prop, obj){
if (arguments.length === 1) return _obj => has(prop, _obj)
if (!obj) return false
return obj[ prop ] !== undefined
}Tests
import { has } from './has'
test('happy', () => {
expect(has('a')({ a : 1 })).toBeTrue()
expect(has('b', { a : 1 })).toBeFalse()
})
test('with non-object', () => {
expect(has('a', undefined)).toEqual(false)
expect(has('a', null)).toEqual(false)
expect(has('a', true)).toEqual(false)
expect(has('a', '')).toEqual(false)
expect(has('a', /a/)).toEqual(false)
})Typescript test
import {has} from 'rambda'
describe('R.has', () => {
it('happy', () => {
const result = has('foo', {a: 1})
const curriedResult = has('bar')({a: 1})
result // $ExpectType boolean
curriedResult // $ExpectType boolean
})
})1 failed Ramda.has specs
💥 Reason for the failure: Rambda method does check properties from the prototype chain
💥 Reason for the failure: Rambda method does check properties from the prototype chain
var R = require('../../../../dist/rambda.js');
var eq = require('./shared/eq');
describe('has', function() {
var fred = {name: 'Fred', age: 23};
var anon = {age: 99};
it('does not check properties from the prototype chain', function() {
var Person = function() {};
Person.prototype.age = function() {};
var bob = new Person();
eq(R.has('age', bob), false);
});
});hasPath
hasPath<T>(
path: string | string[],
input: object
): booleanIt will return true, if input object has truthy path(calculated with R.path).
const path = 'a.b'
const pathAsArray = ['a', 'b']
const obj = {a: {b: []}}
const result = [
R.hasPath(path, obj),
R.hasPath(pathAsArray, obj),
R.hasPath('a.c', obj),
]
// => [true, true, false]Try the above R.hasPath example in Rambda REPL
All Typescript definitions
hasPath<T>(
path: string | string[],
input: object
): boolean;
hasPath<T>(
path: string | string[]
): (input: object) => boolean;R.hasPath source
import { path } from './path'
export function hasPath(maybePath, obj){
if (arguments.length === 1){
return objHolder => hasPath(maybePath, objHolder)
}
return path(maybePath, obj) !== undefined
}Tests
import { hasPath } from './hasPath'
test('when true', () => {
const path = 'a.b'
const obj = { a : { b : [] } }
const result = hasPath(path)(obj)
const expectedResult = true
expect(result).toEqual(expectedResult)
})
test('when false', () => {
const path = 'a.b'
const obj = {}
const result = hasPath(path, obj)
const expectedResult = false
expect(result).toEqual(expectedResult)
})Typescript test
import {hasPath} from 'rambda'
describe('R.hasPath', () => {
it('string path', () => {
const obj = {a: {b: 1}}
const result = hasPath('a.b', obj)
const curriedResult = hasPath('a.c')(obj)
result // $ExpectType boolean
curriedResult // $ExpectType boolean
})
it('array path', () => {
const obj = {a: {b: 1}}
const result = hasPath(['a', 'b'], obj)
const curriedResult = hasPath(['a', 'c'])(obj)
result // $ExpectType boolean
curriedResult // $ExpectType boolean
})
})head
head<T>(listOrString: T[]): T | undefinedIt returns the first element of listOrString.
const result = [
R.head([1, 2, 3]),
R.head('foo')
]
// => [1, 'f']Try the above R.head example in Rambda REPL
All Typescript definitions
head<T>(listOrString: T[]): T | undefined;
head(listOrString: string): string;R.head source
export function head(listOrString){
if (typeof listOrString === 'string') return listOrString[ 0 ] || ''
return listOrString[ 0 ]
}Tests
import { head } from './head'
test('head', () => {
expect(head([ 'fi', 'fo', 'fum' ])).toEqual('fi')
expect(head([])).toEqual(undefined)
expect(head('foo')).toEqual('f')
expect(head('')).toEqual('')
})Typescript test
import {head} from 'rambda'
describe('R.head', () => {
it('string', () => {
const result = head('foo')
result // $ExpectType string
})
it('array', () => {
const result = head([1, 2, 3])
result // $ExpectType number | undefined
})
})identical
identical<T>(x: T, y: T): booleanIt returns true if its arguments a and b are identical.
Otherwise, it returns false.
const obj = {a: 1};
R.identical(obj, obj); //=> true
R.identical(1, 1); //=> true
R.identical(1, '1'); //=> false
R.identical([], []); //=> false
R.identical(0, -0); //=> false
R.identical(NaN, NaN); //=> trueTry the above R.identical example in Rambda REPL
All Typescript definitions
identical<T>(x: T, y: T): boolean;
identical<T>(x: T): (y: T) => boolean;R.identical source
import _objectIs from './_internals/_objectIs'
export function identical(a, b){
if (arguments.length === 1) return _b => identical(a, _b)
return _objectIs(a, b)
}Tests
import { F, T } from '../rambda'
import { _isInteger } from './_internals/_isInteger'
import { _objectIs } from './_internals/_objectIs'
import { identical } from './identical'
test('with boolean', () => {
expect(F()).toBeFalse()
expect(T()).toBeTrue()
})
test('internal isInteger', () => {
expect(_isInteger(1)).toBeTrue()
expect(_isInteger(0.3)).toBeFalse()
})
test('internal objectIs', () => {
expect(_objectIs(1, 1)).toBeTrue()
expect(_objectIs(NaN, NaN)).toBeTrue()
})
test('identical', () => {
const a = {}
expect(identical(100)(100)).toEqual(true)
expect(identical(100, '100')).toEqual(false)
expect(identical('string', 'string')).toEqual(true)
expect(identical([], [])).toEqual(false)
expect(identical(a, a)).toEqual(true)
expect(identical(undefined, undefined)).toEqual(true)
expect(identical(null, undefined)).toEqual(false)
})Typescript test
import {identical} from 'rambda'
describe('R.identical', () => {
it('happy', () => {
const result = identical(4, 1)
const curriedResult = identical(4)(1)
result // $ExpectType boolean
curriedResult // $ExpectType boolean
})
it('with object', () => {
const result = identical({a: 1}, {b: 2})
result // $ExpectType boolean
})
})
/*
in curried version Typescript correctly catch errors
but it doesn't do so in the standart definition
identical({a:1},{b:2})
identical({a:1})({b:2})
*/identity
identity<T>(input: T): TIt just passes back the supplied input argument.
R.identity(7) // => 7Try the above R.identity example in Rambda REPL
All Typescript definitions
identity<T>(input: T): T;R.identity source
export function identity(input){
return input
}Tests
import { identity } from './identity'
test('happy', () => {
expect(identity(7)).toEqual(7)
expect(identity(true)).toEqual(true)
expect(identity({ a : 1 })).toEqual({ a : 1 })
})Typescript test
import {identity} from 'rambda'
describe('R.identity', () => {
it('happy', () => {
const result = identity(4)
result // $ExpectType 4
})
})ifElse
ifElse<T, U>(
condition: (x: T) => boolean,
onTrue: (x: T) => U,
onFalse: (x: T) => U,
): (x: T) => UIt expects condition, onTrue and onFalse functions as inputs and it returns a new function with example name of fn.
When fn`` is called with inputargument, it will return eitheronTrue(input)oronFalse(input)depending oncondition(input)` evaluation.
const fn = R.ifElse(
x => x>10,
x => x*2,
x => x*10
)
const result = [ fn(8), fn(18) ]
// => [80, 36]Try the above R.ifElse example in Rambda REPL
All Typescript definitions
ifElse<T, U>(
condition: (x: T) => boolean,
onTrue: (x: T) => U,
onFalse: (x: T) => U,
): (x: T) => U;
ifElse<T, K, U>(
condition: (x: T, y: K) => boolean,
onTrue: (x: T, y: K) => U,
onFalse: (x: T, y: K) => U,
): (x: T, y: K) => U;R.ifElse source
import { curry } from './curry'
function ifElseFn(
condition, onTrue, onFalse
){
return (...input) => {
const conditionResult =
typeof condition === 'boolean' ? condition : condition(...input)
if (conditionResult === true){
return onTrue(...input)
}
return onFalse(...input)
}
}
export const ifElse = curry(ifElseFn)Tests
import { always } from './always'
import { has } from './has'
import { identity } from './identity'
import { ifElse } from './ifElse'
import { prop } from './prop'
const condition = has('foo')
const v = function (a){
return typeof a === 'number'
}
const t = function (a){
return a + 1
}
const ifFn = x => prop('foo', x).length
const elseFn = () => false
test('happy', () => {
const fn = ifElse(condition, ifFn)(elseFn)
expect(fn({ foo : 'bar' })).toEqual(3)
expect(fn({ fo : 'bar' })).toEqual(false)
})
test('ramda spec', () => {
const ifIsNumber = ifElse(v)
expect(ifIsNumber(t, identity)(15)).toEqual(16)
expect(ifIsNumber(t, identity)('hello')).toEqual('hello')
})
test('pass all arguments', () => {
const identity = function (a){
return a
}
const v = function (){
return true
}
const onTrue = function (a, b){
expect(a).toEqual(123)
expect(b).toEqual('abc')
}
ifElse(
v, onTrue, identity
)(123, 'abc')
})
test('accept constant as condition', () => {
const fn = ifElse(true)(always(true))(always(false))
expect(fn()).toEqual(true)
})
test('accept constant as condition - case 2', () => {
const fn = ifElse(
false, always(true), always(false)
)
expect(fn()).toEqual(false)
})
test('curry 1', () => {
const fn = ifElse(condition, ifFn)(elseFn)
expect(fn({ foo : 'bar' })).toEqual(3)
expect(fn({ fo : 'bar' })).toEqual(false)
})
test('curry 2', () => {
const fn = ifElse(condition)(ifFn)(elseFn)
expect(fn({ foo : 'bar' })).toEqual(3)
expect(fn({ fo : 'bar' })).toEqual(false)
})
test('simple arity of 1', () => {
const condition = x => x > 5
const onTrue = x => x + 1
const onFalse = x => x + 10
const result = ifElse(
condition, onTrue, onFalse
)(1)
expect(result).toBe(11)
})
test('simple arity of 2', () => {
const condition = (x, y) => x + y > 5
const onTrue = (x, y) => x + y + 1
const onFalse = (x, y) => x + y + 10
const result = ifElse(
condition, onTrue, onFalse
)(1, 10)
expect(result).toBe(12)
})Typescript test
import {ifElse} from 'rambda'
describe('R.ifElse', () => {
it('happy', () => {
const condition = (x: number) => x > 5
const onTrue = (x: number) => `foo${x}`
const onFalse = (x: number) => `bar${x}`
const fn = ifElse(condition, onTrue, onFalse)
fn // $ExpectType (x: number) => string
const result = fn(3)
result // $ExpectType string
})
it('arity of 2', () => {
const condition = (x: number, y: string) => x + y.length > 5
const onTrue = (x: number, y: string) => `foo${x}-${y}`
const onFalse = (x: number, y: string) => `bar${x}-${y}`
const fn = ifElse(condition, onTrue, onFalse)
fn // $ExpectType (x: number, y: string) => string
const result = fn(3, 'hello')
result // $ExpectType string
})
})2 failed Ramda.ifElse specs
💥 Reason for the failure: Rambda method doesn't return a curried function
💥 Reason for the failure: Rambda method doesn't return a curried function
var R = require('../../../../dist/rambda.js');
var eq = require('./shared/eq');
describe('ifElse', function() {
var t = function(a) { return a + 1; };
var identity = function(a) { return a; };
var isArray = function(a) { return Object.prototype.toString.call(a) === '[object Array]'; };
it('returns a function whose arity equals the max arity of the three arguments to `ifElse`', function() {
function a0() { return 0; }
function a1(x) { return x; }
function a2(x, y) { return x + y; }
eq(R.ifElse(a0, a1, a2).length, 2);
eq(R.ifElse(a0, a2, a1).length, 2);
eq(R.ifElse(a1, a0, a2).length, 2);
eq(R.ifElse(a1, a2, a0).length, 2);
eq(R.ifElse(a2, a0, a1).length, 2);
eq(R.ifElse(a2, a1, a0).length, 2);
});
it('returns a curried function', function() {
var v = function(a) { return typeof a === 'number'; };
var ifIsNumber = R.ifElse(v);
eq(ifIsNumber(t, identity)(15), 16);
eq(ifIsNumber(t, identity)('hello'), 'hello');
var fn = R.ifElse(R.gt, R.subtract, R.add);
eq(fn(2)(7), 9);
eq(fn(2, 7), 9);
eq(fn(7)(2), 5);
eq(fn(7, 2), 5);
});
});inc
inc(x: number): numberIt increments a number.
R.inc(1) // => 2Try the above R.inc example in Rambda REPL
All Typescript definitions
inc(x: number): number;R.inc source
export const inc = x => x + 1Tests
import { inc } from './inc'
test('happy', () => {
expect(inc(1)).toBe(2)
})includes
includes(valueToFind: string, input: ReadonlyArray<string> | string): booleanIf input is string, then this method work as native String.includes.
If input is array, then R.equals is used to define if valueToFind belongs to the list.
const result = [
R.includes('oo', 'foo'),
R.includes({a: 1}, [{a: 1}])
]
// => [true, true ]Try the above R.includes example in Rambda REPL
All Typescript definitions
includes(valueToFind: string, input: ReadonlyArray<string> | string): boolean;
includes(valueToFind: string): (input: ReadonlyArray<string> | string) => boolean;
includes<T>(valueToFind: T, input: ReadonlyArray<T>): boolean;
includes<T>(valueToFind: T): (input: ReadonlyArray<T>) => boolean;R.includes source
import { _isArray } from './_internals/_isArray'
import { equals } from './equals'
export function includes(valueToFind, input){
if (arguments.length === 1) return _input => includes(valueToFind, _input)
if (typeof input === 'string'){
return input.includes(valueToFind)
}
if (!input){
throw new TypeError(`Cannot read property \'indexOf\' of ${ input }`)
}
if (!_isArray(input)) return false
let index = -1
while (++index < input.length){
if (equals(input[ index ], valueToFind)){
return true
}
}
return false
}Tests
import R from 'ramda'
import { includes } from './includes'
test('includes with string', () => {
const str = 'more is less'
expect(includes('less')(str)).toBeTrue()
expect(R.includes('less')(str)).toBeTrue()
expect(includes('never', str)).toBeFalse()
expect(R.includes('never', str)).toBeFalse()
})
test('includes with array', () => {
const arr = [ 1, 2, 3 ]
expect(includes(2)(arr)).toBeTrue()
expect(R.includes(2)(arr)).toBeTrue()
expect(includes(4, arr)).toBeFalse()
expect(R.includes(4, arr)).toBeFalse()
})
test('with wrong input that does not throw', () => {
const result = includes(1, /foo/g)
const ramdaResult = R.includes(1, /foo/g)
expect(result).toBeFalse()
expect(ramdaResult).toBeFalse()
})
test('throws on wrong input - match ramda behaviour', () => {
expect(() => includes(2, null)).toThrowWithMessage(TypeError,
'Cannot read property \'indexOf\' of null')
expect(() => R.includes(2, null)).toThrowWithMessage(TypeError,
'Cannot read property \'indexOf\' of null')
expect(() => includes(2, undefined)).toThrowWithMessage(TypeError,
'Cannot read property \'indexOf\' of undefined')
expect(() => R.includes(2, undefined)).toThrowWithMessage(TypeError,
'Cannot read property \'indexOf\' of undefined')
})Typescript test
import {includes} from 'ramda'
const list = [{a: {b: '1'}}, {a: {c: '2'}}, {a: {b: '3'}}]
describe('R.includes', () => {
it('happy', () => {
const result = includes({a: {b: '1'}}, list)
/*
should work:
const resultCurried = includes({a: {b: '1'}})(list)
*/
result // $ExpectType boolean
result // $ExpectType boolean
})
it('with string', () => {
const result = includes('oo', 'foo')
const resultCurried = includes('oo')('foo')
result // $ExpectType boolean
resultCurried // $ExpectType boolean
})
})1 failed Ramda.includes specs
💥 Reason for the failure: Ramda method pass to equals method if available
💥 Reason for the failure: Ramda method pass to equals method if available
var R = require('../../../../dist/rambda.js');
var eq = require('./shared/eq');
describe('includes', function() {
it('has R.equals semantics', function() {
function Just(x) { this.value = x; }
Just.prototype.equals = function(x) {
return x instanceof Just && R.equals(x.value, this.value);
};
eq(R.includes(0, [-0]), false);
eq(R.includes(-0, [0]), false);
eq(R.includes(NaN, [NaN]), true);
eq(R.includes(new Just([42]), [new Just([42])]), true);
});
});indexBy
indexBy<T>(condition: (x: T) => string, list: ReadonlyArray<T>): { [key: string]: T }It generates object with properties provided by condition and values provided by list array.
If condition is a function, then all list members are passed through it.
If condition is a string, then all list members are passed through R.path(condition).
const list = [ {id: 10}, {id: 20} ]
const withFunction = R.indexBy(
x => x.id,
list
)
const withString = R.indexBy(
'id',
list
)
const result = [
withFunction,
R.equals(withFunction, withString)
]
// => [ { 10: {id: 10}, 20: {id: 20} }, true ]Try the above R.indexBy example in Rambda REPL
All Typescript definitions
indexBy<T>(condition: (x: T) => string, list: ReadonlyArray<T>): { [key: string]: T };
indexBy<T>(condition: string, list: ReadonlyArray<T>): { [key: string]: T };
indexBy<T>(condition: (x: T) => string): (list: ReadonlyArray<T>) => { [key: string]: T };
indexBy<T>(condition: string): (list: ReadonlyArray<T>) => { [key: string]: T };R.indexBy source
import { path } from './path'
function indexByPath(pathInput, list){
const toReturn = {}
for (let i = 0; i < list.length; i++){
const item = list[ i ]
toReturn[ path(pathInput, item) ] = item
}
return toReturn
}
export function indexBy(condition, list){
if (arguments.length === 1){
return _list => indexBy(condition, _list)
}
if (typeof condition === 'string'){
return indexByPath(condition, list)
}
const toReturn = {}
for (let i = 0; i < list.length; i++){
const item = list[ i ]
toReturn[ condition(item) ] = item
}
return toReturn
}Tests
import { indexBy } from './indexBy'
import { prop } from './prop'
test('happy', () => {
const list = [
{ id : 1 },
{
id : 1,
a : 2,
},
{ id : 2 },
{ id : 10 },
{ id : 'a' },
]
expect(indexBy(prop('id'))(list)).toEqual({
1 : {
id : 1,
a : 2,
},
2 : { id : 2 },
10 : { id : 10 },
a : { id : 'a' },
})
})
test('with string as condition', () => {
const list = [ { id : 1 }, { id : 2 }, { id : 10 }, { id : 'a' } ]
const standardResult = indexBy(obj => obj.id, list)
const suggestionResult = indexBy('id', list)
expect(standardResult).toEqual(suggestionResult)
})
test('with string - bad path', () => {
const list = [
{
a : {
b : 1,
c : 2,
},
},
{ a : { c : 4 } },
{},
{
a : {
b : 10,
c : 20,
},
},
]
const result = indexBy('a.b', list)
const expected = {
1 : {
a : {
b : 1,
c : 2,
},
},
10 : {
a : {
b : 10,
c : 20,
},
},
undefined : {},
}
expect(result).toEqual(expected)
})Typescript test
import {indexBy} from 'rambda'
const list = [{a: {b: '1'}}, {a: {c: '2'}}, {a: {b: '3'}}]
describe('indexBy', () => {
it('happy', () => {
const result = indexBy<any>(x => x.a.b, list)
const resultCurried = indexBy<any>(x => x.a.b)(list)
result // $ExpectType { [key: string]: any; }
resultCurried // $ExpectType { [key: string]: any; }
})
it('with string', () => {
const result = indexBy<any>('a.b', list)
const resultCurried = indexBy<any>('a.b')(list)
result // $ExpectType { [key: string]: any; }
resultCurried // $ExpectType { [key: string]: any; }
})
it('with interface', () => {
interface Foo {
a: string,
}
const interfaceList = [{a: 'foo'}, {a: 'bar'}]
const result = indexBy<Foo>(x => {
x.a // $ExpectType string
return x.a
}, interfaceList)
const resultCurried = indexBy<Foo>(x => {
x.a // $ExpectType string
return x.a
})(interfaceList)
result // $ExpectType { [key: string]: Foo; }
resultCurried // $ExpectType { [key: string]: Foo; }
})
})1 failed Ramda.indexBy specs
💥 Reason for the failure: Ramda method can act as a transducer
💥 Reason for the failure: Ramda method can act as a transducer
var R = require('../../../../dist/rambda.js');
var eq = require('./shared/eq');
describe('indexBy', function() {
it('can act as a transducer', function() {
var list = [{id: 'xyz', title: 'A'}, {id: 'abc', title: 'B'}];
var transducer = R.compose(
R.indexBy(R.prop('id')),
R.map(R.pipe(
R.adjust(0, R.toUpper),
R.adjust(1, R.omit(['id']))
)));
var result = R.into({}, transducer, list);
eq(result, {ABC: {title: 'B'}, XYZ: {title: 'A'}});
});
});indexOf
indexOf<T>(valueToFind: T, list: ReadonlyArray<T>): numberIt returns the index of the first element of list equals to valueToFind.
If there is no such element, it returns -1.
const list = [0, 1, 2, 3]
const result = [
R.indexOf(2, list),
R.indexOf(0, list)
]
// => [2, -1]Try the above R.indexOf example in Rambda REPL
All Typescript definitions
indexOf<T>(valueToFind: T, list: ReadonlyArray<T>): number;
indexOf<T>(valueToFind: T): (list: ReadonlyArray<T>) => number;R.indexOf source
export function indexOf(valueToFind, list){
if (arguments.length === 1){
return _list => indexOf(valueToFind, _list)
}
let index = -1
const { length } = list
while (++index < length){
if (list[ index ] === valueToFind){
return index
}
}
return -1
}Tests
import { indexOf } from './indexOf'
test('happy', () => {
expect(indexOf(3, [ 1, 2, 3, 4 ])).toEqual(2)
expect(indexOf(10)([ 1, 2, 3, 4 ])).toEqual(-1)
})Typescript test
import {indexOf} from 'rambda'
describe('R.indexOf', () => {
it('happy', () => {
const list = [1, 2, 3]
const result = indexOf(1, list)
const curriedResult = indexOf(1)(list)
result // $ExpectType number
curriedResult // $ExpectType number
})
})2 failed Ramda.indexOf specs
💥 Reason for the failure: Ramda method dispatches to indexOf method
💥 Reason for the failure: Ramda method dispatches to indexOf method
var R = require('../../../../dist/rambda.js');
var eq = require('./shared/eq');
describe('indexOf', function() {
var input = [1, 2, 3, 4, 5];
var list = [1, 2, 3];
list[-2] = 4; // Throw a wrench in the gears by assigning a non-valid array index as object property.
it('has R.equals semantics', function() {
function Just(x) { this.value = x; }
Just.prototype.equals = function(x) {
return x instanceof Just && R.equals(x.value, this.value);
};
eq(R.indexOf(0, [-0]), -1);
eq(R.indexOf(-0, [0]), -1);
eq(R.indexOf(NaN, [NaN]), 0);
eq(R.indexOf(new Just([42]), [new Just([42])]), 0);
});
it('dispatches to `indexOf` method', function() {
function Empty() {}
Empty.prototype.indexOf = R.always(-1);
function List(head, tail) {
this.head = head;
this.tail = tail;
}
List.prototype.indexOf = function(x) {
var idx = this.tail.indexOf(x);
return this.head === x ? 0 : idx >= 0 ? 1 + idx : -1;
};
var list = new List('b',
new List('a',
new List('n',
new List('a',
new List('n',
new List('a',
new Empty()
)
)
)
)
)
);
eq(R.indexOf('a', 'banana'), 1);
eq(R.indexOf('x', 'banana'), -1);
eq(R.indexOf('a', list), 1);
eq(R.indexOf('x', list), -1);
});
});init
init<T>(listOrString: ReadonlyArray<T>): T[]It returns all but the last element of listOrString.
const result = [
R.init([1, 2, 3]) ,
R.init('foo') // => 'fo'
]
// => [[1, 2], 'fo']Try the above R.init example in Rambda REPL
All Typescript definitions
init<T>(listOrString: ReadonlyArray<T>): T[];
init(listOrString: string): string;R.init source
import baseSlice from './_internals/baseSlice'
export function init(listOrString){
if (typeof listOrString === 'string') return listOrString.slice(0, -1)
return listOrString.length ? baseSlice(
listOrString, 0, -1
) : []
}Tests
import { init } from './init'
test('with array', () => {
expect(init([ 1, 2, 3 ])).toEqual([ 1, 2 ])
expect(init([ 1, 2 ])).toEqual([ 1 ])
expect(init([ 1 ])).toEqual([])
expect(init([])).toEqual([])
expect(init([])).toEqual([])
expect(init([ 1 ])).toEqual([])
})
test('with string', () => {
expect(init('foo')).toEqual('fo')
expect(init('f')).toEqual('')
expect(init('')).toEqual('')
})Typescript test
import {init} from 'rambda'
describe('R.init', () => {
it('with string', () => {
const result = init('foo')
result // $ExpectType string
})
it('with list', () => {
const result = init([1, 2, 3])
result // $ExpectType number[]
})
})intersection
intersection<T>(listA: ReadonlyArray<T>, listB: ReadonlyArray<T>): T[]It loops throw listA and listB and returns the intersection of the two according to R.equals.
const listA = [ { id : 1 }, { id : 2 }, { id : 3 }, { id : 4 } ]
const listB = [ { id : 3 }, { id : 4 }, { id : 5 }, { id : 6 } ]
const result = intersection(listA, listB)
// => [{ id : 3 }, { id : 4 }]Try the above R.intersection example in Rambda REPL
All Typescript definitions
intersection<T>(listA: ReadonlyArray<T>, listB: ReadonlyArray<T>): T[];
intersection<T>(listA: ReadonlyArray<T>): (listB: ReadonlyArray<T>) => T[];R.intersection source
import { filter } from './filter'
import { includes } from './includes'
export function intersection(listA, listB){
if (arguments.length === 1) return _list => intersection(listA, _list)
return filter(value => includes(value, listB), listA)
}Tests
import { intersection } from './intersection'
test('intersection', () => {
const list1 = [ 1, 2, 3, 4 ]
const list2 = [ 3, 4, 5, 6 ]
expect(intersection(list1)(list2)).toEqual([ 3, 4 ])
expect(intersection([], [])).toEqual([])
})
test('intersection with objects', () => {
const list1 = [ { id : 1 }, { id : 2 }, { id : 3 }, { id : 4 } ]
const list2 = [ { id : 3 }, { id : 4 }, { id : 5 }, { id : 6 } ]
expect(intersection(list1)(list2)).toEqual([ { id : 3 }, { id : 4 } ])
})Typescript test
import {intersection} from 'rambda'
const list1 = [1, 2, 3]
const list2 = [1, 3, 5]
describe('R.intersection', () => {
it('happy', () => {
const result = intersection(list1, list2)
result // $ExpectType number[]
const curriedResult = intersection(list1)(list2)
curriedResult // $ExpectType number[]
})
})intersperse
intersperse<T>(separator: T, list: ReadonlyArray<T>): T[]It adds a separator between members of list.
const list = [ 0, 1, 2, 3 ]
const separator = '|'
const result = intersperse(separator, list)
// => [0, '|', 1, '|', 2, '|', 3]Try the above R.intersperse example in Rambda REPL
All Typescript definitions
intersperse<T>(separator: T, list: ReadonlyArray<T>): T[];
intersperse<T>(separator: T): (list: ReadonlyArray<T>) => T[];R.intersperse source
export function intersperse(separator, list){
if (arguments.length === 1) return _list => intersperse(separator, _list)
let index = -1
const len = list.length
const willReturn = []
while (++index < len){
if (index === len - 1){
willReturn.push(list[ index ])
} else {
willReturn.push(list[ index ], separator)
}
}
return willReturn
}Tests
import { intersperse } from './intersperse'
test('intersperse', () => {
const list = [ { id : 1 }, { id : 2 }, { id : 10 }, { id : 'a' } ]
expect(intersperse('!', list)).toEqual([
{ id : 1 },
'!',
{ id : 2 },
'!',
{ id : 10 },
'!',
{ id : 'a' },
])
expect(intersperse('!')([])).toEqual([])
})Typescript test
import {intersperse} from 'rambda'
describe('R.intersperse', () => {
it('happy', () => {
const result = intersperse(1, [1, 2, 3])
result // $ExpectType number[]
})
it('curried', () => {
const result = intersperse('|')(['foo', 'bar'])
result // $ExpectType string[]
})
})is
is(targetPrototype: any, x: any): booleanIt returns true if x is instance of targetPrototype.
const result = [
R.is(String, 'foo'),
R.is(Array, 1)
]
// => [true, false]Try the above R.is example in Rambda REPL
All Typescript definitions
is(targetPrototype: any, x: any): boolean;
is(targetPrototype: any): (x: any) => boolean;R.is source
export function is(targetPrototype, x){
if (arguments.length === 1) return _x => is(targetPrototype, _x)
return (
x != null && x.constructor === targetPrototype ||
x instanceof targetPrototype
)
}Tests
import { is } from './is'
test('works with built-in types', () => {
expect(is(Array, undefined)).toBeFalse()
expect(is(Array)([])).toBeTrue()
expect(is(Boolean, new Boolean(false))).toBeTrue()
expect(is(Date, new Date())).toBeTrue()
expect(is(Function, () => {})).toBeTrue()
expect(is(Number, new Number(0))).toBeTrue()
expect(is(Object, {})).toBeTrue()
expect(is(RegExp, /(?:)/)).toBeTrue()
expect(is(String, new String(''))).toBeTrue()
})
test('works with user-defined types', () => {
function Foo(){}
function Bar(){}
Bar.prototype = new Foo()
const foo = new Foo()
const bar = new Bar()
expect(is(Foo, foo)).toBeTrue()
expect(is(Bar, bar)).toBeTrue()
expect(is(Foo, bar)).toBeTrue()
expect(is(Bar, foo)).toBeFalse()
})
test('does not coerce', () => {
expect(is(Boolean, 1)).toBeFalse()
expect(is(Number, '1')).toBeFalse()
expect(is(Number, false)).toBeFalse()
})
test('recognizes primitives as their object equivalents', () => {
expect(is(Boolean, false)).toBeTrue()
expect(is(Number, 0)).toBeTrue()
expect(is(String, '')).toBeTrue()
})
test('does not consider primitives to be instances of Object', () => {
expect(is(Object, false)).toBeFalse()
expect(is(Object, 0)).toBeFalse()
expect(is(Object, '')).toBeFalse()
})Typescript test
import {is} from 'rambda'
describe('R.is', () => {
it('happy', () => {
const result = is(String, 'foo')
result // $ExpectType boolean
})
it('curried', () => {
const result = is(Number)(1)
result // $ExpectType boolean
})
})isEmpty
isEmpty<T>(x: T): booleanIt returns true if x is empty.
const result = [
R.isEmpty(''),
R.isEmpty({ x : 0 })
]
// => [true, false]Try the above R.isEmpty example in Rambda REPL
All Typescript definitions
isEmpty<T>(x: T): boolean;R.isEmpty source
import { type } from './type'
export function isEmpty(input){
const inputType = type(input)
if ([ 'Undefined', 'NaN', 'Number', 'Null' ].includes(inputType))
return false
if (!input) return true
if (inputType === 'Object'){
return Object.keys(input).length === 0
}
if (inputType === 'Array'){
return input.length === 0
}
return false
}Tests
import { isEmpty } from './isEmpty'
test('happy', () => {
expect(isEmpty(undefined)).toEqual(false)
expect(isEmpty('')).toEqual(true)
expect(isEmpty(null)).toEqual(false)
expect(isEmpty(' ')).toEqual(false)
expect(isEmpty(new RegExp(''))).toEqual(false)
expect(isEmpty([])).toEqual(true)
expect(isEmpty([ [] ])).toEqual(false)
expect(isEmpty({})).toEqual(true)
expect(isEmpty({ x : 0 })).toEqual(false)
expect(isEmpty(0)).toEqual(false)
expect(isEmpty(NaN)).toEqual(false)
expect(isEmpty([ '' ])).toEqual(false)
})Typescript test
import {isEmpty} from 'rambda'
describe('R.isEmpty', () => {
it('happy', () => {
const result = isEmpty('foo')
result // $ExpectType boolean
})
})1 failed Ramda.isEmpty specs
💥 Reason for the failure: Ramda method supports typed arrays
💥 Reason for the failure: Ramda method supports typed arrays
var R = require('../../../../dist/rambda.js');
var eq = require('./shared/eq');
describe('isEmpty', function() {
it('returns true for empty typed array', function() {
eq(R.isEmpty(Uint8Array.from('')), true);
eq(R.isEmpty(Float32Array.from('')), true);
eq(R.isEmpty(new Float32Array([])), true);
eq(R.isEmpty(Uint8Array.from('1')), false);
eq(R.isEmpty(Float32Array.from('1')), false);
eq(R.isEmpty(new Float32Array([1])), false);
});
});isNil
isNil(x: any): x is null | undefinedIt returns true if x is either null or undefined.
const result = [
R.isNil(null),
R.isNil(1),
]
// => [true, false]Try the above R.isNil example in Rambda REPL
All Typescript definitions
isNil(x: any): x is null | undefined;R.isNil source
export function isNil(x){
return x === undefined || x === null
}Tests
import { isNil } from './isNil'
test('happy', () => {
expect(isNil(null)).toBeTrue()
expect(isNil(undefined)).toBeTrue()
expect(isNil([])).toBeFalse()
})join
join<T>(glue: string, list: ReadonlyArray<T>): stringIt returns a string of all list instances joined with a glue.
R.join('-', [1, 2, 3]) // => '1-2-3'Try the above R.join example in Rambda REPL
All Typescript definitions
join<T>(glue: string, list: ReadonlyArray<T>): string;
join<T>(glue: string): (list: ReadonlyArray<T>) => string;R.join source
export function join(glue, list){
if (arguments.length === 1) return _list => join(glue, _list)
return list.join(glue)
}Tests
import { join } from './join'
test('curry', () => {
expect(join('|')([ 'foo', 'bar', 'baz' ])).toEqual('foo|bar|baz')
expect(join('|', [ 1, 2, 3 ])).toEqual('1|2|3')
const spacer = join(' ')
expect(spacer([ 'a', 2, 3.4 ])).toEqual('a 2 3.4')
})Typescript test
import {join} from 'rambda'
describe('R.join', () => {
it('happy', () => {
const result = join('|', [1, 2, 3])
result // $ExpectType string
})
})keys
keys<T extends object>(x: T): (keyof T)[]It applies Object.keys over x and returns its keys.
R.keys({a:1, b:2}) // => ['a', 'b']Try the above R.keys example in Rambda REPL
All Typescript definitions
keys<T extends object>(x: T): (keyof T)[];
keys<T>(x: T): string[];R.keys source
export function keys(x){
return Object.keys(x)
}Tests
import { keys } from './keys'
test('happy', () => {
expect(keys({ a : 1 })).toEqual([ 'a' ])
})Typescript test
import {keys} from 'rambda'
const obj = {a: 1, b: 2}
describe('R.keys', () => {
it('happy', () => {
const result = keys(obj)
result // $ExpectType ("b" | "a")[]
})
})1 failed Ramda.keys specs
💥 Reason for the failure: Ramda method works for primitives
💥 Reason for the failure: Ramda method works for primitives
var R = require('../../../../dist/rambda.js');
var eq = require('./shared/eq');
describe('keys', function() {
var obj = {a: 100, b: [1, 2, 3], c: {x: 200, y: 300}, d: 'D', e: null, f: undefined};
function C() { this.a = 100; this.b = 200; }
C.prototype.x = function() { return 'x'; };
C.prototype.y = 'y';
var cobj = new C();
it('works for primitives', function() {
eq(R.keys(null), []);
eq(R.keys(undefined), []);
eq(R.keys(55), []);
eq(R.keys('foo'), []);
eq(R.keys(true), []);
eq(R.keys(false), []);
eq(R.keys(NaN), []);
eq(R.keys(Infinity), []);
eq(R.keys([]), []);
});
});last
last(str: string): stringIt returns the last element of input, as the input can be either a string or an array.
const result = [
R.last([1, 2, 3]),
R.last('foo'),
]
// => [3, 'o']Try the above R.last example in Rambda REPL
All Typescript definitions
last(str: string): string;
last(emptyList: readonly []): undefined;
last<T extends any>(list: readonly T[]): T | undefined;R.last source
export function last(listOrString){
if (typeof listOrString === 'string'){
return listOrString[ listOrString.length - 1 ] || ''
}
return listOrString[ listOrString.length - 1 ]
}Tests
import { last } from './last'
test('happy', () => {
expect(last([ 'foo', 'bar', 'baz' ])).toEqual('baz')
expect(last([])).toEqual(undefined)
expect(last('abc')).toEqual('c')
expect(last('')).toEqual('')
})Typescript test
import {last} from 'rambda'
describe('R.last', () => {
it('string', () => {
const result = last('foo')
result // $ExpectType string
})
it('array', () => {
const result = last([1, 2, 3])
result // $ExpectType number | undefined
})
it('empty array', () => {
const result = last([])
result // $ExpectType undefined
})
})lastIndexOf
lastIndexOf<T>(target: T, list: ReadonlyArray<T>): numberIt returns the last index of target in list array.
R.equals is used to determine equality between target and members of list.
If there is no such index, then -1 is returned.
const list = [1, 2, 3, 1, 2, 3]
const result = [
R.lastIndexOf(2, list),
R.lastIndexOf(4, list),
]
// => [4, -1]Try the above R.lastIndexOf example in Rambda REPL
All Typescript definitions
lastIndexOf<T>(target: T, list: ReadonlyArray<T>): number;
lastIndexOf<T>(target: T): (list: ReadonlyArray<T>) => number;R.lastIndexOf source
import { equals } from './equals'
export function lastIndexOf(target, list){
if (arguments.length === 1) return _list => lastIndexOf(target, _list)
let index = list.length
while (--index > 0){
if (equals(list[ index ], target)){
return index
}
}
return -1
}Tests
import { lastIndexOf } from './lastIndexOf'
test('happy', () => {
const a = lastIndexOf(1, [ 1, 2, 3, 1, 2 ])
const b = lastIndexOf(1)([ 1, 2, 3, 1, 2 ])
expect(a).toEqual(3)
expect(b).toEqual(3)
})
test('false', () => {
const a = lastIndexOf(10, [ 1, 2, 3, 1, 2 ])
expect(a).toEqual(-1)
})Typescript test
import {lastIndexOf} from 'rambda'
const list = [1, 2, 3]
describe('R.lastIndexOf', () => {
it('happy', () => {
const result = lastIndexOf(2, list)
result // $ExpectType number
})
it('curried', () => {
const result = lastIndexOf(2)(list)
result // $ExpectType number
})
})3 failed Ramda.lastIndexOf specs
💥 Reason for the failure: Ramda method dispatches to lastIndexOf method
💥 Reason for the failure: Ramda method dispatches to lastIndexOf method
var R = require('../../../../dist/rambda.js');
var eq = require('./shared/eq');
describe('lastIndexOf', function() {
var input = [1, 2, 3, 4, 5, 1];
var list = ['a', 1, 'a'];
list[-2] = 'a'; // Throw a wrench in the gears by assigning a non-valid array index as object property.
it('has R.equals semantics', function() {
function Just(x) { this.value = x; }
Just.prototype.equals = function(x) {
return x instanceof Just && R.equals(x.value, this.value);
};
eq(R.lastIndexOf(0, [-0]), -1);
eq(R.lastIndexOf(-0, [0]), -1);
eq(R.lastIndexOf(NaN, [NaN]), 0);
eq(R.lastIndexOf(new Just([42]), [new Just([42])]), 0);
});
it('dispatches to `lastIndexOf` method', function() {
function Empty() {}
Empty.prototype.lastIndexOf = R.always(-1);
function List(head, tail) {
this.head = head;
this.tail = tail;
}
List.prototype.lastIndexOf = function(x) {
var idx = this.tail.lastIndexOf(x);
return idx >= 0 ? 1 + idx : this.head === x ? 0 : -1;
};
var list = new List('b',
new List('a',
new List('n',
new List('a',
new List('n',
new List('a',
new Empty()
)
)
)
)
)
);
eq(R.lastIndexOf('a', 'banana'), 5);
eq(R.lastIndexOf('x', 'banana'), -1);
eq(R.lastIndexOf('a', list), 5);
eq(R.lastIndexOf('x', list), -1);
});
it('finds function, compared by identity', function() {
var f = function() {};
var g = function() {};
var list = [g, f, g, f];
eq(R.lastIndexOf(f, list), 3);
});
});length
length<T>(listOrString: ReadonlyArray<T>): numberIt returns the length property of listOrString.
const result = [
R.length([1, 2, 3, 4]),
R.length('foo'),
]
// => [4, 3]Try the above R.length example in Rambda REPL
All Typescript definitions
length<T>(listOrString: ReadonlyArray<T>): number;R.length source
export function length(x){
if (!x && x !== '' || x.length === undefined){
return NaN
}
return x.length
}Tests
import { length } from './length'
test('happy', () => {
expect(length('foo')).toEqual(3)
expect(length([ 1, 2, 3 ])).toEqual(3)
expect(length([])).toEqual(0)
})
test('with empty string', () => {
expect(length('')).toEqual(0)
})
test('with bad input returns NaN', () => {
expect(length(0)).toBeNaN()
expect(length({})).toBeNaN()
expect(length(null)).toBeNaN()
expect(length(undefined)).toBeNaN()
})1 failed Ramda.length specs
💥 Reason for the failure: Ramda method supports object with length method
💥 Reason for the failure: Ramda method supports object with length method
var R = require('../../../../dist/rambda.js');
var eq = require('./shared/eq');
describe('length', function() {
it('returns the length of a string', function() {
eq(R.length(''), 0);
eq(R.length('xyz'), 3);
});
it('returns NaN for length property of unexpected type', function() {
eq(R.identical(NaN, R.length({length: ''})), true);
eq(R.identical(NaN, R.length({length: '1.23'})), true);
eq(R.identical(NaN, R.length({length: null})), true);
eq(R.identical(NaN, R.length({length: undefined})), true);
eq(R.identical(NaN, R.length({})), true);
});
});lens
lens<T, U, V>(getter: (s: T) => U, setter: (a: U, s: T) => V): LensIt returns a lens for the given getter and setter functions.
The getter gets the value of the focus; the setter sets the value of the focus.
The setter should not mutate the data structure.
const xLens = R.lens(R.prop('x'), R.assoc('x'));
R.view(xLens, {x: 1, y: 2}) // => 1
R.set(xLens, 4, {x: 1, y: 2}) // => {x: 4, y: 2}
R.over(xLens, R.negate, {x: 1, y: 2}) // => {x: -1, y: 2}Try the above R.lens example in Rambda REPL
All Typescript definitions
lens<T, U, V>(getter: (s: T) => U, setter: (a: U, s: T) => V): Lens;
lens<T, U, V>(getter: (s: T) => U, setter: (a: U, s: T) => V): Lens;R.lens source
export function lens(getter, setter){
if (arguments.length === 1) return _setter => lens(getter, _setter)
return function (functor){
return function (target){
return functor(getter(target)).map(focus => setter(focus, target))
}
}
}Tests
import { assoc } from './assoc'
import { compose } from './compose'
import { lens } from './lens'
import { lensIndex } from './lensIndex'
import { lensPath } from './lensPath'
import { lensProp } from './lensProp'
import { over } from './over'
import { prop } from './prop'
import { set } from './set'
import { toUpper } from './toUpper'
import { view } from './view'
const alice = {
name : 'Alice Jones',
address : [ '22 Walnut St', 'San Francisco', 'CA' ],
pets : {
dog : 'joker',
cat : 'batman',
},
}
const nameLens = lens(prop('name'), assoc('name'))
const addressLens = lensProp('address')
const headLens = lensIndex(0)
const dogLens = lensPath('pets.dog')
test('view', () => {
expect(view(nameLens, alice)).toEqual('Alice Jones')
expect(view(dogLens, alice)).toEqual('joker')
expect(view(headLens, alice.address)).toEqual('22 Walnut St')
})
test('over', () => {
expect(over(
nameLens, toUpper, alice
)).toEqual({
name : 'ALICE JONES',
address : [ '22 Walnut St', 'San Francisco', 'CA' ],
pets : {
dog : 'joker',
cat : 'batman',
},
})
expect(over(
dogLens, toUpper, alice
)).toEqual({
name : 'Alice Jones',
address : [ '22 Walnut St', 'San Francisco', 'CA' ],
pets : {
dog : 'JOKER',
cat : 'batman',
},
})
expect(over(headLens, toUpper)(alice.address)).toEqual([
'22 WALNUT ST',
'San Francisco',
'CA',
])
})
test('set', () => {
expect(set(
nameLens, 'Alice Smith', alice
)).toEqual({
name : 'Alice Smith',
address : [ '22 Walnut St', 'San Francisco', 'CA' ],
pets : {
dog : 'joker',
cat : 'batman',
},
})
expect(set(
dogLens, 'bane', alice
)).toEqual({
name : 'Alice Jones',
address : [ '22 Walnut St', 'San Francisco', 'CA' ],
pets : {
dog : 'bane',
cat : 'batman',
},
})
expect(set(
headLens, '52 Crane Ave', alice.address
)).toEqual([
'52 Crane Ave',
'San Francisco',
'CA',
])
})
test('composed lenses', () => {
const composedStreetLens = compose(addressLens, headLens)
const composedDogLens = compose(lensPath('pets'), lensPath('dog'))
expect(view(composedDogLens, alice)).toEqual(view(dogLens, alice))
expect(view(composedStreetLens, alice)).toEqual('22 Walnut St')
expect(over(
composedStreetLens, toUpper, alice
)).toEqual({
name : 'Alice Jones',
address : [ '22 WALNUT ST', 'San Francisco', 'CA' ],
pets : {
dog : 'joker',
cat : 'batman',
},
})
expect(set(
composedStreetLens, '52 Crane Ave', alice
)).toEqual({
name : 'Alice Jones',
address : [ '52 Crane Ave', 'San Francisco', 'CA' ],
pets : {
dog : 'joker',
cat : 'batman',
},
})
})Typescript test
import {lens, lensIndex, lensPath, lensProp, view} from 'rambda'
import {assoc} from 'ramda'
interface Dictionary<T> {
[index: string]: T,
}
interface Input {
name: string,
address: string[],
pets: Dictionary<string>,
}
const MockObject: Input = {
name: 'Alice Jones',
address: ['22 Walnut St', 'San Francisco', 'CA'],
pets: {dog: 'joker', cat: 'batman'},
}
const nameLens = lens<Input, string, string>((x: Input) => {
return x.name
}, assoc('name'))
const addressLens = lensProp('address')
const headLens = lensIndex(0)
const dogLens = lensPath(['pets', 'dog'])
const dogLensAsString = lensPath('pets.doc')
describe('lenses', () => {
it('lens', () => {
const result = view<Input, string>(nameLens, MockObject)
result // $ExpectType string
})
it('lens path', () => {
const result = view<Input, string>(dogLens, MockObject)
result // $ExpectType string
})
it('lens path as string', () => {
const result = view<Input, string>(dogLensAsString, MockObject)
result // $ExpectType string
})
it('lens prop', () => {
const result = view<Input, string>(addressLens, MockObject)
result // $ExpectType string
})
it('lens index', () => {
const result = view<Input['address'], string>(
headLens,
MockObject.address
)
result // $ExpectType string
})
})lensIndex
lensIndex(index: number): LensIt returns a lens that focuses on specified index.
const list = ['a', 'b', 'c']
const headLens = R.lensIndex(0)
R.view(headLens, list) // => 'a'
R.set(headLens, 'x', list) // => ['x', 'b', 'c']
R.over(headLens, R.toUpper, list) // => ['A', 'b', 'c']Try the above R.lensIndex example in Rambda REPL
All Typescript definitions
lensIndex(index: number): Lens;R.lensIndex source
import { lens } from './lens'
import { nth } from './nth'
import { update } from './update'
export function lensIndex(index){
return lens(nth(index), update(index))
}Tests
import { compose } from './compose'
import { keys } from './keys'
import { lensIndex } from './lensIndex'
import { over } from './over'
import { set } from './set'
import { view } from './view'
const testList = [ { a : 1 }, { b : 2 }, { c : 3 } ]
test('focuses list element at the specified index', () => {
expect(view(lensIndex(0), testList)).toEqual({ a : 1 })
})
test('returns undefined if the specified index does not exist', () => {
expect(view(lensIndex(10), testList)).toEqual(undefined)
})
test('sets the list value at the specified index', () => {
expect(set(
lensIndex(0), 0, testList
)).toEqual([ 0, { b : 2 }, { c : 3 } ])
})
test('applies function to the value at the specified list index', () => {
expect(over(
lensIndex(2), keys, testList
)).toEqual([ { a : 1 }, { b : 2 }, [ 'c' ] ])
})
test('can be composed', () => {
const nestedList = [ 0, [ 10, 11, 12 ], 1, 2 ]
const composedLens = compose(lensIndex(1), lensIndex(0))
expect(view(composedLens, nestedList)).toEqual(10)
})
test('set s (get s) === s', () => {
expect(set(
lensIndex(0), view(lensIndex(0), testList), testList
)).toEqual(testList)
})
test('get (set s v) === v', () => {
expect(view(lensIndex(0), set(
lensIndex(0), 0, testList
))).toEqual(0)
})
test('get (set(set s v1) v2) === v2', () => {
expect(view(lensIndex(0),
set(
lensIndex(0), 11, set(
lensIndex(0), 10, testList
)
))).toEqual(11)
})lensPath
lensPath(path: RamdaPath): LensIt returns a lens that focuses on specified path.
const lensPath = R.lensPath(['x', 0, 'y'])
const input = {x: [{y: 2, z: 3}, {y: 4, z: 5}]}
R.view(lensPath, input) //=> 2
R.set(lensPath, 1, input)
//=> {x: [{y: 1, z: 3}, {y: 4, z: 5}]}
R.over(xHeadYLens, R.negate, input)
//=> {x: [{y: -2, z: 3}, {y: 4, z: 5}]}Try the above R.lensPath example in Rambda REPL
All Typescript definitions
lensPath(path: RamdaPath): Lens;
lensPath(path: string): Lens;R.lensPath source
import { assocPath } from './assocPath'
import { lens } from './lens'
import { path } from './path'
export function lensPath(key){
return lens(path(key), assocPath(key))
}Tests
import { compose } from './compose'
import { identity } from './identity'
import { inc } from './inc'
import { lensPath } from './lensPath'
import { lensProp } from './lensProp'
import { over } from './over'
import { set } from './set'
import { view } from './view'
const testObj = {
a : [ { b : 1 }, { b : 2 } ],
d : 3,
}
test('view', () => {
expect(view(lensPath('d'), testObj)).toEqual(3)
expect(view(lensPath('a.0.b'), testObj)).toEqual(1)
// this is different to ramda, ramda will return a clone of the input object
expect(view(lensPath(''), testObj)).toEqual(undefined)
})
test('set', () => {
expect(set(
lensProp('d'), 0, testObj
)).toEqual({
a : [ { b : 1 }, { b : 2 } ],
d : 0,
})
expect(set(
lensPath('a.0.b'), 0, testObj
)).toEqual({
a : [ { b : 0 }, { b : 2 } ],
d : 3,
})
expect(set(
lensPath('a.0.X'), 0, testObj
)).toEqual({
a : [
{
b : 1,
X : 0,
},
{ b : 2 },
],
d : 3,
})
expect(set(
lensPath([]), 0, testObj
)).toEqual(0)
})
test('over', () => {
expect(over(
lensPath('d'), inc, testObj
)).toEqual({
a : [ { b : 1 }, { b : 2 } ],
d : 4,
})
expect(over(
lensPath('a.1.b'), inc, testObj
)).toEqual({
a : [ { b : 1 }, { b : 3 } ],
d : 3,
})
expect(over(
lensProp('X'), identity, testObj
)).toEqual({
a : [ { b : 1 }, { b : 2 } ],
d : 3,
X : undefined,
})
expect(over(
lensPath('a.0.X'), identity, testObj
)).toEqual({
a : [
{
b : 1,
X : undefined,
},
{ b : 2 },
],
d : 3,
})
})
test('compose', () => {
const composedLens = compose(lensPath('a'), lensPath('1.b'))
expect(view(composedLens, testObj)).toEqual(2)
})
test('set s (get s) === s', () => {
expect(set(
lensPath([ 'd' ]), view(lensPath([ 'd' ]), testObj), testObj
)).toEqual(testObj)
expect(set(
lensPath([ 'a', 0, 'b' ]),
view(lensPath([ 'a', 0, 'b' ]), testObj),
testObj
)).toEqual(testObj)
})
test('get (set s v) === v', () => {
expect(view(lensPath([ 'd' ]), set(
lensPath([ 'd' ]), 0, testObj
))).toEqual(0)
expect(view(lensPath([ 'a', 0, 'b' ]), set(
lensPath([ 'a', 0, 'b' ]), 0, testObj
))).toEqual(0)
})
test('get (set(set s v1) v2) === v2', () => {
const p = [ 'd' ]
const q = [ 'a', 0, 'b' ]
expect(view(lensPath(p), set(
lensPath(p), 11, set(
lensPath(p), 10, testObj
)
))).toEqual(11)
expect(view(lensPath(q), set(
lensPath(q), 11, set(
lensPath(q), 10, testObj
)
))).toEqual(11)
})lensProp
lensProp(prop: string): {
<T, U>(obj: T): UIt returns a lens that focuses on specified property prop.
const xLens = R.lensProp('x');
const input = {x: 1, y: 2}
R.view(xLens, input) // => 1
R.set(xLens, 4, input)
// => {x: 4, y: 2}
R.over(xLens, R.negate, input)
// => {x: -1, y: 2}Try the above R.lensProp example in Rambda REPL
All Typescript definitions
lensProp(prop: string): {
<T, U>(obj: T): U;
set<T, U, V>(val: T, obj: U): V;
};R.lensProp source
import { assoc } from './assoc'
import { lens } from './lens'
import { prop } from './prop'
export function lensProp(key){
return lens(prop(key), assoc(key))
}Tests
import { compose } from './compose'
import { identity } from './identity'
import { inc } from './inc'
import { lensProp } from './lensProp'
import { over } from './over'
import { set } from './set'
import { view } from './view'
const testObj = {
a : 1,
b : 2,
c : 3,
}
test('focuses object the specified object property', () => {
expect(view(lensProp('a'), testObj)).toEqual(1)
})
test('returns undefined if the specified property does not exist', () => {
expect(view(lensProp('X'), testObj)).toEqual(undefined)
})
test('sets the value of the object property specified', () => {
expect(set(
lensProp('a'), 0, testObj
)).toEqual({
a : 0,
b : 2,
c : 3,
})
})
test('adds the property to the object if it doesn\'t exist', () => {
expect(set(
lensProp('d'), 4, testObj
)).toEqual({
a : 1,
b : 2,
c : 3,
d : 4,
})
})
test('applies function to the value of the specified object property', () => {
expect(over(
lensProp('a'), inc, testObj
)).toEqual({
a : 2,
b : 2,
c : 3,
})
})
test('applies function to undefined and adds the property if it doesn\'t exist', () => {
expect(over(
lensProp('X'), identity, testObj
)).toEqual({
a : 1,
b : 2,
c : 3,
X : undefined,
})
})
test('can be composed', () => {
const nestedObj = {
a : { b : 1 },
c : 2,
}
const composedLens = compose(lensProp('a'), lensProp('b'))
expect(view(composedLens, nestedObj)).toEqual(1)
})
test('set s (get s) === s', () => {
expect(set(
lensProp('a'), view(lensProp('a'), testObj), testObj
)).toEqual(testObj)
})
test('get (set s v) === v', () => {
expect(view(lensProp('a'), set(
lensProp('a'), 0, testObj
))).toEqual(0)
})
test('get (set(set s v1) v2) === v2', () => {
expect(view(lensProp('a'),
set(
lensProp('a'), 11, set(
lensProp('a'), 10, testObj
)
))).toEqual(11)
})map
map<T, U>(fn: MapFunctionObject<T, U>, list: Dictionary<T>): Dictionary<U>It returns the result of looping through list with fn.
It works with both array and object.
const fn = (x, i) => (x * 2) + i
const fnWhenObject = (val, prop)=>{
return `${prop}-${val}`
}
const list = [1, 2]
const obj = {a: 1, b: 2}
const result = [
R.map(fn, list),
R.map(fnWhenObject, obj)
]
// => [ [2, 5], {a: 'a-1', b: 'b-2'}]Try the above R.map example in Rambda REPL
All Typescript definitions
map<T, U>(fn: MapFunctionObject<T, U>, list: Dictionary<T>): Dictionary<U>;
map<T, U>(fn: MapFunctionArray<T, U>, list: T[]): U[];
map<T, U>(fn: MapFunctionArray<T, U>): (list: T[]) => U[];
map<T, U, S>(fn: MapFunctionObject<T, U>): (list: Dictionary<T>) => Dictionary<U>;
map<T>(fn: MapFunctionArray<T, T>): (list: T[]) => T[];
map<T>(fn: MapFunctionArray<T, T>, list: ReadonlyArray<T>): T[];R.map source
import { _isArray } from './_internals/_isArray'
import { _keys } from './_internals/_keys'
export function map(fn, list){
if (arguments.length === 1) return _list => map(fn, _list)
if (list === undefined){
return []
}
if (_isArray(list)){
let index = 0
const len = list.length
const willReturn = Array(len)
while (index < len){
willReturn[ index ] = fn(
list[ index ], index, list
)
index++
}
return willReturn
}
let index = 0
const keys = _keys(list)
const len = keys.length
const willReturn = {}
while (index < len){
const key = keys[ index ]
willReturn[ key ] = fn(
list[ key ], key, list
)
index++
}
return willReturn
}Tests
import { map } from './map'
const double = x => x * 2
const sampleObject = {
a : 1,
b : 2,
c : 3,
d : 4,
}
test('with array', () => {
expect(map(double, [ 1, 2, 3 ])).toEqual([ 2, 4, 6 ])
})
test('pass index as second argument', () => {
map((x, i) => {
expect(i).toBeNumber()
},
[ 10, 20, 30 ])
})
test('with object', () => {
const obj = {
a : 1,
b : 2,
}
expect(map(double, obj)).toEqual({
a : 2,
b : 4,
})
})
test('pass input object as third argument', () => {
const obj = {
a : 1,
b : 2,
}
const iterator = (
val, prop, inputObject
) => {
expect(inputObject).toEqual(obj)
return val * 2
}
expect(map(iterator, obj)).toEqual({
a : 2,
b : 4,
})
})
test('with object passes property as second argument', () => {
map((_, prop) => {
expect(typeof prop).toEqual('string')
})(sampleObject)
})
/**
* https://github.com/selfrefactor/rambda/issues/77
*/
test('when undefined instead of array', () => {
expect(map(double, undefined)).toEqual([])
})Typescript test
import {map} from 'rambda'
describe('R.map with arrays', () => {
it('iterable returns the same type as the input', () => {
const result = map<number>(
(a, b) => {
a // $ExpectType number
b // $ExpectType number
return a + 2
},
[1, 2, 3]
)
result // $ExpectType number[]
})
it('iterable returns the same type as the input - curried', () => {
const result = map<number>((a, b) => {
a // $ExpectType number
b // $ExpectType number
return a + 2
})([1, 2, 3])
result // $ExpectType number[]
})
it('iterable with index argument', () => {
const result = map<number, string>(
(a, b) => {
a // $ExpectType number
b // $ExpectType number
return `${a}`
},
[1, 2, 3]
)
result // $ExpectType string[]
})
it('iterable with index argument - curried', () => {
const result = map<number, string>((a, b) => {
a // $ExpectType number
b // $ExpectType number
return `${a}`
})([1, 2, 3])
result // $ExpectType string[]
})
})
describe('R.map with objects', () => {
it('iterable with all three arguments - curried', () => {
// It requires dummy third typing argument
// in order to identify compared to curry typings for arrays
// ============================================
const result = map<number, string, any>((a, b, c) => {
a // $ExpectType number
b // $ExpectType string
c // $ExpectType Dictionary<number>
return `${a}`
})({a: 1, b: 2})
result // $ExpectType Dictionary<string>
})
it('iterable with all three arguments', () => {
const result = map<number, string>(
(a, b, c) => {
a // $ExpectType number
b // $ExpectType string
c // $ExpectType Dictionary<number>
return `${a}`
},
{a: 1, b: 2}
)
result // $ExpectType Dictionary<string>
})
it('iterable with property argument', () => {
const result = map<number, string>(
(a, b) => {
a // $ExpectType number
b // $ExpectType string
return `${a}`
},
{a: 1, b: 2}
)
result // $ExpectType Dictionary<string>
})
it('iterable with no property argument', () => {
const result = map<number, string>(
a => {
a // $ExpectType number
return `${a}`
},
{a: 1, b: 2}
)
result // $ExpectType Dictionary<string>
})
})match
match(regExpression: RegExp, str: string): string[]Curried version of String.prototype.match which returns empty array, when there is no match.
const result = [
R.match('a', 'foo'),
R.match(/([a-z]a)/g, 'bananas')
]
// => [[], ['ba', 'na', 'na']]Try the above R.match example in Rambda REPL
All Typescript definitions
match(regExpression: RegExp, str: string): string[];
match(regExpression: RegExp): (str: string) => string[];R.match source
export function match(pattern, input){
if (arguments.length === 1) return _input => match(pattern, _input)
const willReturn = input.match(pattern)
return willReturn === null ? [] : willReturn
}Tests
import { equals } from './equals'
import { match } from './match'
test('happy', () => {
expect(match(/a./g)('foo bar baz')).toEqual([ 'ar', 'az' ])
})
test('fallback', () => {
expect(match(/a./g)('foo')).toEqual([])
})
test('with string', () => {
expect(match('a', 'foo')).toEqual([])
expect(equals(match('o', 'foo'), [ 'o' ])).toBeTrue()
})
test('throwing', () => {
expect(() => {
match(/a./g, null)
}).toThrowWithMessage(TypeError, 'Cannot read property \'match\' of null')
})Typescript test
import {match} from 'rambda'
const str = 'foo bar'
describe('R.match', () => {
it('happy', () => {
const result = match(/foo/, str)
result // $ExpectType string[]
})
it('curried', () => {
const result = match(/foo/)(str)
result // $ExpectType string[]
})
})mathMod
mathMod(x: number, y: number): numberR.mathMod behaves like the modulo operator should mathematically, unlike the % operator (and by extension, R.modulo). So while -17 % 5 is -2, mathMod(-17, 5) is 3.
const result = [
R.mathMod(-17, 5),
R.mathMod(17, 5),
R.mathMod(17, -5),
R.mathMod(17, 0)
]
// => [3, 2, NaN, NaN]Try the above R.mathMod example in Rambda REPL
All Typescript definitions
mathMod(x: number, y: number): number;
mathMod(x: number): (y: number) => number;R.mathMod source
import _isInteger from './_internals/_isInteger'
export function mathMod(x, y){
if (arguments.length === 1) return _y => mathMod(x, _y)
if (!_isInteger(x) || !_isInteger(y) || y < 1) return NaN
return (x % y + y) % y
}Tests
import { mathMod } from './mathMod'
test('happy', () => {
expect(mathMod(-17)(5)).toEqual(3)
expect(mathMod(17, 5)).toEqual(2)
expect(mathMod(17, -5)).toBeNaN()
expect(mathMod(17, 0)).toBeNaN()
expect(mathMod('17', 5)).toBeNaN()
expect(mathMod({}, 2)).toBeNaN()
expect(mathMod([], 2)).toBeNaN()
expect(mathMod(Symbol(), 2)).toBeNaN()
})Typescript test
import {mathMod} from 'rambda'
const first = 1
const second = 2
describe('R.mathMod', () => {
it('happy', () => {
const result = mathMod(first, second)
result // $ExpectType number
})
it('curried', () => {
const result = mathMod(first, second)
result // $ExpectType number
})
})max
max<T extends Ord>(x: T, y: T): TIt returns the greater value between x and y.
const result = [
R.max(5, 7),
R.max('bar', 'foo'),
]
// => [7, 'foo']Try the above R.max example in Rambda REPL
All Typescript definitions
max<T extends Ord>(x: T, y: T): T;
max<T extends Ord>(x: T): (y: T) => T;R.max source
export function max(x, y){
if (arguments.length === 1) return _y => max(x, _y)
return y > x ? y : x
}Tests
import { max } from './max'
test('with number', () => {
expect(max(2, 1)).toBe(2)
})
test('with string', () => {
expect(max('foo')('bar')).toBe('foo')
expect(max('bar')('baz')).toBe('baz')
})Typescript test
import {max} from 'rambda'
const first = 1
const second = 2
describe('R.max', () => {
it('happy', () => {
const result = max(first, second)
result // $ExpectType 1 | 2
})
it('curried', () => {
const result = max(first, second)
result // $ExpectType 1 | 2
})
it('curried - cann pass type', () => {
const result = max<number>(first, second)
result // $ExpectType number
})
it('can pass type', () => {
const result = max<number>(first, second)
result // $ExpectType number
})
})maxBy
maxBy<T>(compareFn: (input: T) => Ord, x: T, y: T): TIt returns the greater value between x and y according to compareFn function.
const compareFn = Math.abs
R.maxBy(compareFn, 5, -7) // => -7Try the above R.maxBy example in Rambda REPL
All Typescript definitions
maxBy<T>(compareFn: (input: T) => Ord, x: T, y: T): T;
maxBy<T>(compareFn: (input: T) => Ord, x: T): (y: T) => T;
maxBy<T>(compareFn: (input: T) => Ord): FunctionToolbelt.Curry<(x: T, y: T) => T>;R.maxBy source
import { curry } from './curry'
export function maxByFn(
compareFn, x, y
){
return compareFn(y) > compareFn(x) ? y : x
}
export const maxBy = curry(maxByFn)Tests
import { maxBy } from './maxBy'
test('happy', () => {
expect(maxBy(
Math.abs, -5, 2
)).toEqual(-5)
})
test('curried', () => {
expect(maxBy(Math.abs)(2, -5)).toEqual(-5)
expect(maxBy(Math.abs)(2)(-5)).toEqual(-5)
})Typescript test
import {maxBy} from 'rambda'
const compareFn = (x: number) => x % 2 === 0 ? 1 : -1
const first = 1
const second = 2
describe('R.maxBy', () => {
it('happy', () => {
const result = maxBy(compareFn, first, second)
result // $ExpectType 1 | 2
})
it('curried 1', () => {
const result = maxBy(compareFn)(first, second)
result // $ExpectType number
})
it('curried 2', () => {
const result = maxBy<number>(compareFn, first)(second)
result // $ExpectType number
})
it('curried 3', () => {
const result = maxBy(compareFn)(first)(second)
result // $ExpectType number
})
})mean
mean(list: ReadonlyArray<number>): numberIt returns the mean value of list input.
R.mean([ 2, 7 ])
// => 4.5Try the above R.mean example in Rambda REPL
All Typescript definitions
mean(list: ReadonlyArray<number>): number;R.mean source
import { sum } from './sum'
export function mean(list){
return sum(list) / list.length
}Tests
import { mean } from './mean'
test('happy', () => {
expect(mean([ 2, 7 ])).toBe(4.5)
})
test('with NaN', () => {
expect(mean([])).toBeNaN()
})Typescript test
import {mean} from 'rambda'
describe('R.mean', () => {
it('happy', () => {
const result = mean([1, 2, 3])
result // $ExpectType number
})
})median
median(list: ReadonlyArray<number>): numberIt returns the median value of list input.
R.median([ 7, 2, 10, 9 ]) // => 8Try the above R.median example in Rambda REPL
All Typescript definitions
median(list: ReadonlyArray<number>): number;R.median source
import { mean } from './mean'
export function median(list){
const len = list.length
if (len === 0) return NaN
const width = 2 - len % 2
const idx = (len - width) / 2
return mean(Array.prototype.slice
.call(list, 0)
.sort((a, b) => {
if (a === b) return 0
return a < b ? -1 : 1
})
.slice(idx, idx + width))
}Tests
import { median } from './median'
test('happy', () => {
expect(median([ 2 ])).toEqual(2)
expect(median([ 7, 2, 10, 9 ])).toEqual(8)
})
test('with empty array', () => {
expect(median([])).toBeNaN()
})Typescript test
import {median} from 'rambda'
describe('R.median', () => {
it('happy', () => {
const result = median([1, 2, 3])
result // $ExpectType number
})
})merge
merge<O1 extends object, O2 extends object>(target: O1, newProps: O2): Merge<O2, O1, 'flat'>It creates a copy of target object with overidden newProps properties.
const target = { 'foo': 0, 'bar': 1 }
const newProps = { 'foo': 7 }
const result = R.merge(target, newProps)
// => { 'foo': 7, 'bar': 1 }Try the above R.merge example in Rambda REPL
All Typescript definitions
merge<O1 extends object, O2 extends object>(target: O1, newProps: O2): Merge<O2, O1, 'flat'>;
merge<O1 extends object>(target: O1): <O2 extends object>(newProps: O2) => Merge<O2, O1, 'flat'>;R.merge source
export function merge(target, newProps){
if (arguments.length === 1) return _newProps => merge(target, _newProps)
return Object.assign(
{}, target || {}, newProps || {}
)
}Tests
import { merge } from './merge'
const obj = {
foo : 1,
bar : 2,
}
test('happy', () => {
expect(merge(obj, { bar : 20 })).toEqual({
foo : 1,
bar : 20,
})
})
test('curry', () => {
expect(merge(obj)({ baz : 3 })).toEqual({
foo : 1,
bar : 2,
baz : 3,
})
})
/**
* https://github.com/selfrefactor/rambda/issues/77
*/
test('when undefined or null instead of object', () => {
expect(merge(null, undefined)).toEqual({})
expect(merge(obj, null)).toEqual(obj)
expect(merge(obj, undefined)).toEqual(obj)
expect(merge(undefined, obj)).toEqual(obj)
})Typescript test
import {merge} from 'rambda'
describe('R.merge', () => {
const result = merge({foo: 1}, {bar: 2})
const curriedResult = merge({foo: 1})({bar: 2})
result.foo // $ExpectType number
result.bar // $ExpectType number
curriedResult.bar // $ExpectType number
})mergeAll
mergeAll<T>(list: object[]): TIt merges all objects of list array sequentially and returns the result.
const list = [
{a: 1},
{b: 2},
{c: 3}
]
const result = R.mergeAll(list)
const expected = {
a: 1,
b: 2,
c: 3
}
// => `result` is equal to `expected`Try the above R.mergeAll example in Rambda REPL
All Typescript definitions
mergeAll<T>(list: object[]): T;
mergeAll(list: object[]): object;R.mergeAll source
import { map } from './map'
import { merge } from './merge'
export function mergeAll(arr){
let willReturn = {}
map(val => {
willReturn = merge(willReturn, val)
}, arr)
return willReturn
}Tests
import { mergeAll } from './mergeAll'
test('case 1', () => {
const arr = [ { a : 1 }, { b : 2 }, { c : 3 } ]
const expectedResult = {
a : 1,
b : 2,
c : 3,
}
expect(mergeAll(arr)).toEqual(expectedResult)
})
test('case 2', () => {
expect(mergeAll([ { foo : 1 }, { bar : 2 }, { baz : 3 } ])).toEqual({
foo : 1,
bar : 2,
baz : 3,
})
})Typescript test
import {mergeAll} from 'rambda'
describe('R.mergeAll', () => {
it('with passing type', () => {
interface Output {
foo: number,
bar: number,
}
const result = mergeAll<Output>([{foo: 1}, {bar: 2}])
result.foo // $ExpectType number
result.bar // $ExpectType number
})
it('without passing type', () => {
const result = mergeAll([{foo: 1}, {bar: 2}])
result // $ExpectType unknown
})
})mergeDeepRight
mergeDeepRight<O1 extends object, O2 extends object>(x: O1, y: O2): Merge<O2, O1, 'deep'>Creates a new object with the own properties of the first object merged with the own properties of the second object. If a key exists in both objects:
- and both values are objects, the two values will be recursively merged
- otherwise the value from the second object will be used.
All Typescript definitions
mergeDeepRight<O1 extends object, O2 extends object>(x: O1, y: O2): Merge<O2, O1, 'deep'>;
mergeDeepRight<O1 extends object>(x: O1): <O2 extends object>(y: O2) => Merge<O2, O1, 'deep'>;R.mergeDeepRight source
import { type } from './type'
export function mergeDeepRight(target, source){
if (arguments.length === 1){
return sourceHolder => mergeDeepRight(target, sourceHolder)
}
const willReturn = JSON.parse(JSON.stringify(target))
Object.keys(source).forEach(key => {
if (type(source[ key ]) === 'Object'){
if (type(target[ key ]) === 'Object'){
willReturn[ key ] = mergeDeepRight(target[ key ], source[ key ])
} else {
willReturn[ key ] = source[ key ]
}
} else {
willReturn[ key ] = source[ key ]
}
})
return willReturn
}Tests
// import { mergeDeepRight } from 'ramda'
import { mergeDeepRight } from './mergeDeepRight'
const slave = {
name : 'evilMe',
age : 10,
contact : {
a : 1,
email : 'foo@example.com',
},
}
const master = {
age : 40,
contact : { email : 'baz@example.com' },
songs : { title : 'Remains the same' },
}
test('happy', () => {
const result = mergeDeepRight(slave, master)
const curryResult = mergeDeepRight(slave)(master)
const expected = {
age : 40,
name : 'evilMe',
contact : {
a : 1,
email : 'baz@example.com',
},
songs : { title : 'Remains the same' },
}
expect(result).toEqual(expected)
expect(curryResult).toEqual(expected)
})
test('ramda compatible test 1', () => {
const a = {
w : 1,
x : 2,
y : { z : 3 },
}
const b = {
a : 4,
b : 5,
c : { d : 6 },
}
const result = mergeDeepRight(a, b)
const expected = {
w : 1,
x : 2,
y : { z : 3 },
a : 4,
b : 5,
c : { d : 6 },
}
expect(result).toEqual(expected)
})
test('ramda compatible test 2', () => {
const a = {
a : {
b : 1,
c : 2,
},
y : 0,
}
const b = {
a : {
b : 3,
d : 4,
},
z : 0,
}
const result = mergeDeepRight(a, b)
const expected = {
a : {
b : 3,
c : 2,
d : 4,
},
y : 0,
z : 0,
}
expect(result).toEqual(expected)
})
test('ramda compatible test 3', () => {
const a = {
w : 1,
x : { y : 2 },
}
const result = mergeDeepRight(a, { x : { y : 3 } })
const expected = {
w : 1,
x : { y : 3 },
}
expect(result).toEqual(expected)
})Typescript test
import {mergeDeepRight} from 'rambda'
describe('R.mergeDeepRight', () => {
const result = mergeDeepRight({foo: {bar: 1}}, {foo: {bar: 2}})
result.foo.bar // $ExpectType number
})mergeLeft
mergeLeft<O1 extends object, O2 extends object>(target: O1, newProps: O2): Merge<O2, O1, 'flat'>Same as R.merge, but in opposite direction.
const result = R.mergeLeft(
{a: 10},
{a: 1, b: 2}
)
// => {a:10, b: 2}Try the above R.mergeLeft example in Rambda REPL
All Typescript definitions
mergeLeft<O1 extends object, O2 extends object>(target: O1, newProps: O2): Merge<O2, O1, 'flat'>;
mergeLeft<O1 extends object>(target: O1): <O2 extends object>(newProps: O2) => Merge<O2, O1, 'flat'>;R.mergeLeft source
import { merge } from './merge'
export function mergeLeft(x, y){
if (arguments.length === 1) return _y => mergeLeft(x, _y)
return merge(y, x)
}Tests
import { mergeLeft } from './mergeLeft'
const obj = {
foo : 1,
bar : 2,
}
test('happy', () => {
expect(mergeLeft({ bar : 20 }, obj)).toEqual({
foo : 1,
bar : 20,
})
})
test('curry', () => {
expect(mergeLeft({ baz : 3 })(obj)).toEqual({
foo : 1,
bar : 2,
baz : 3,
})
})
test('when undefined or null instead of object', () => {
expect(mergeLeft(null, undefined)).toEqual({})
expect(mergeLeft(obj, null)).toEqual(obj)
expect(mergeLeft(obj, undefined)).toEqual(obj)
expect(mergeLeft(undefined, obj)).toEqual(obj)
})Typescript test
import {mergeLeft} from 'rambda'
describe('R.mergeLeft', () => {
const result = mergeLeft({foo: 1}, {bar: 2})
const curriedResult = mergeLeft({foo: 1})({bar: 2})
result.foo // $ExpectType number
result.bar // $ExpectType number
curriedResult.bar // $ExpectType number
})min
min<T extends Ord>(x: T, y: T): TIt returns the lesser value between x and y.
const result = [
R.min(5, 7),
R.min('bar', 'foo'),
]
// => [5, 'bar']Try the above R.min example in Rambda REPL
All Typescript definitions
min<T extends Ord>(x: T, y: T): T;
min<T extends Ord>(x: T): (y: T) => T;R.min source
export function min(x, y){
if (arguments.length === 1) return _y => min(x, _y)
return y < x ? y : x
}Tests
import { min } from './min'
test('happy', () => {
expect(min(2, 1)).toBe(1)
expect(min(2)(1)).toBe(1)
})Typescript test
import {min} from 'rambda'
const first = 1
const second = 2
describe('R.min', () => {
it('happy', () => {
const result = min(first, second)
result // $ExpectType 1 | 2
})
it('curried', () => {
const result = min(first, second)
result // $ExpectType 1 | 2
})
it('curried - cann pass type', () => {
const result = min<number>(first, second)
result // $ExpectType number
})
it('can pass type', () => {
const result = min<number>(first, second)
result // $ExpectType number
})
})minBy
minBy<T>(compareFn: (input: T) => Ord, x: T, y: T): TIt returns the lesser value between x and y according to compareFn function.
const compareFn = Math.abs
R.minBy(compareFn, -5, 2) // => -5Try the above R.minBy example in Rambda REPL
All Typescript definitions
minBy<T>(compareFn: (input: T) => Ord, x: T, y: T): T;
minBy<T>(compareFn: (input: T) => Ord, x: T): (y: T) => T;
minBy<T>(compareFn: (input: T) => Ord): FunctionToolbelt.Curry<(x: T, y: T) => T>;R.minBy source
import { curry } from './curry'
export function minByFn(
compareFn, x, y
){
return compareFn(y) < compareFn(x) ? y : x
}
export const minBy = curry(minByFn)Tests
import { minBy } from './minBy'
test('happy', () => {
expect(minBy(
Math.abs, -5, 2
)).toEqual(2)
})
test('curried', () => {
expect(minBy(Math.abs)(2, -5)).toEqual(2)
expect(minBy(Math.abs)(2)(-5)).toEqual(2)
})Typescript test
import {minBy} from 'rambda'
const compareFn = (x: number) => x % 2 === 0 ? 1 : -1
const first = 1
const second = 2
describe('R.minBy', () => {
it('happy', () => {
const result = minBy(compareFn, first, second)
result // $ExpectType 1 | 2
})
it('curried 1', () => {
const result = minBy(compareFn)(first, second)
result // $ExpectType number
})
it('curried 2', () => {
/*
Than should be the case, but passing type is required for some reason
*/
const result = minBy<number>(compareFn, first)(second)
result // $ExpectType number
})
it('curried 3', () => {
const result = minBy(compareFn)(first)(second)
result // $ExpectType number
})
})modulo
modulo(x: number, y: number): numberCurried version of x%y.
R.modulo(17, 3) // => 2Try the above R.modulo example in Rambda REPL
All Typescript definitions
modulo(x: number, y: number): number;
modulo(x: number): (y: number) => number;R.modulo source
export function modulo(x, y){
if (arguments.length === 1) return _y => modulo(x, _y)
return x % y
}Tests
import { modulo } from './modulo'
test('happy', () => {
expect(modulo(17, 3)).toEqual(2)
expect(modulo(15)(6)).toEqual(3)
})Typescript test
import {modulo} from 'rambda'
describe('R.modulo', () => {
it('happy', () => {
const result = modulo(4, 1)
result // $ExpectType number
})
it('curried', () => {
const result = modulo(4)(1)
result // $ExpectType number
})
})move
move<T>(fromIndex: number, toIndex: number, list: readonly T[]): T[]It returns a copy of list with exchanged fromIndex and toIndex elements.
const list = [1, 2, 3]
const result = R.move(0, 1, list)
// => [2, 1, 3]Try the above R.move example in Rambda REPL
All Typescript definitions
move<T>(fromIndex: number, toIndex: number, list: readonly T[]): T[];
move(fromIndex: number, toIndex: number): <T>(list: readonly T[]) => T[];
move(fromIndex: number): {
<T>(toIndex: number, list: readonly T[]): T[];
(toIndex: number): <T>(list: readonly T[]) => T[];
};R.move source
import { curry } from './curry'
function moveFn(
fromIndex, toIndex, list
){
if (fromIndex < 0 || toIndex < 0){
throw new Error('Rambda.move does not support negative indexes')
}
if (fromIndex > list.length - 1 || toIndex > list.length - 1) return list
const clone = list.slice()
clone[ fromIndex ] = list[ toIndex ]
clone[ toIndex ] = list[ fromIndex ]
return clone
}
export const move = curry(moveFn)Tests
import { move } from './move'
const list = [ 1, 2, 3, 4 ]
test('happy', () => {
const result = move(
0, 1, list
)
expect(result).toEqual([ 2, 1, 3, 4 ])
})
test('with negative index', () => {
const errorMessage = 'Rambda.move does not support negative indexes'
expect(() => move(
0, -1, list
)).toThrowWithMessage(Error, errorMessage)
expect(() => move(
-1, 0, list
)).toThrowWithMessage(Error, errorMessage)
})
test('when indexes are outside the list outbounds', () => {
const result1 = move(
10, 1, list
)
const result2 = move(
1, 10, list
)
expect(result1).toEqual(list)
expect(result2).toEqual(list)
})Typescript test
import {move} from 'rambda'
const list = [1, 2, 3]
describe('R.move', () => {
it('happy', () => {
const result = move(0, 1, list)
result // $ExpectType number[]
})
it('curried 1', () => {
const result = move(0, 1)(list)
result // $ExpectType number[]
})
it('curried 2', () => {
const result = move(0)(1)(list)
result // $ExpectType number[]
})
})2 failed Ramda.move specs
💥 Reason for the failure: Ramda method does not support negative indexes
multiply
multiply(x: number, y: number): numberCurried version of x*y.
R.multiply(2, 4) // => 8Try the above R.multiply example in Rambda REPL
All Typescript definitions
multiply(x: number, y: number): number;
multiply(x: number): (y: number) => number;R.multiply source
export function multiply(x, y){
if (arguments.length === 1) return _y => multiply(x, _y)
return x * y
}Tests
import { multiply } from './multiply'
test('happy', () => {
expect(multiply(2, 4)).toEqual(8)
expect(multiply(2)(4)).toEqual(8)
})Typescript test
import {multiply} from 'rambda'
describe('R.multiply', () => {
it('happy', () => {
const result = multiply(4, 1)
result // $ExpectType number
})
it('curried', () => {
const result = multiply(4)(1)
result // $ExpectType number
})
})negate
negate(x: number): numberR.negate(420)// => -420Try the above R.negate example in Rambda REPL
All Typescript definitions
negate(x: number): number;R.negate source
export function negate(x){
return -x
}Tests
import { negate } from './negate'
test('negate', () => {
expect(negate(420)).toEqual(-420)
expect(negate(-13)).toEqual(13)
})none
none<T>(predicate: (x: T, index: number) => boolean, list: ReadonlyArray<T>): booleanIt returns true, if all members of array list returns false, when applied as argument to predicate function.
const list = [ 0, 1, 2, 3, 4 ]
const predicate = x => x > 6
const result = R.none(predicate, arr)
// => trueTry the above R.none example in Rambda REPL
All Typescript definitions
none<T>(predicate: (x: T, index: number) => boolean, list: ReadonlyArray<T>): boolean;
none<T>(predicate: (x: T) => boolean, list: ReadonlyArray<T>): boolean;
none<T>(predicate: (x: T, index: number) => boolean): (list: ReadonlyArray<T>) => boolean;
none<T>(predicate: (x: T) => boolean): (list: ReadonlyArray<T>) => boolean;R.none source
export function none(predicate, list){
if (arguments.length === 1) return _list => none(predicate, _list)
for (let i = 0; i < list.length; i++){
if (!predicate(list[ i ], i)) return true
}
return false
}Tests
import { none } from './none'
const isEven = n => n % 2 === 0
const isOdd = n => n % 2 === 1
const arr = [ 1, 3, 5, 7, 9, 11 ]
test('when true', () => {
expect(none(isEven, arr)).toBeTrue()
})
test('when false curried', () => {
expect(none(isOdd)(arr)).toBeFalse()
})
test('passes index to predicate', () => {
none((x, i) => {
expect(typeof x).toBe('number')
expect(typeof i).toBe('number')
})([ 1, 2, 3 ])
})Typescript test
import {none} from 'rambda'
describe('R.none', () => {
it('happy', () => {
const result = none(
x => {
x // $ExpectType number
return x > 0
},
[1, 2, 3]
)
result // $ExpectType boolean
})
it('pass index', () => {
const result = none(
(x, i) => {
x // $ExpectType number
i // $ExpectType number
return x > 0
},
[1, 2, 3]
)
result // $ExpectType boolean
})
it('pass index + curry', () => {
const result = none<number>((x, i) => {
x // $ExpectType number
i // $ExpectType number
return x > 0
})([1, 2, 3])
result // $ExpectType boolean
})
it('curried needs a type', () => {
const result = none<number>(x => {
x // $ExpectType number
return x > 0
})([1, 2, 3])
result // $ExpectType boolean
})
})not
not(input: any): booleanIt returns a boolean negated version of input.
R.not(false) // trueTry the above R.not example in Rambda REPL
All Typescript definitions
not(input: any): boolean;R.not source
export function not(input){
return !input
}Tests
import { not } from './not'
test('not', () => {
expect(not(false)).toEqual(true)
expect(not(true)).toEqual(false)
expect(not(0)).toEqual(true)
expect(not(1)).toEqual(false)
})Typescript test
import {not} from 'rambda'
describe('R.not', () => {
it('happy', () => {
const result = not(4)
result // $ExpectType boolean
})
})nth
nth<T>(index: number, list: ReadonlyArray<T>): T | undefinedCurried version of list[index].
const list = [1, 2, 3]
const str = 'foo'
const result = [
R.nth(2, list),
R.nth(6, list),
R.nth(0, str),
]
// => [3, undefined, 'f']Try the above R.nth example in Rambda REPL
All Typescript definitions
nth<T>(index: number, list: ReadonlyArray<T>): T | undefined;
nth(index: number): <T>(list: ReadonlyArray<T>) => T | undefined;R.nth source
export function nth(index, list){
if (arguments.length === 1) return _list => nth(index, _list)
const idx = index < 0 ? list.length + index : index
return Object.prototype.toString.call(list) === '[object String]' ?
list.charAt(idx) :
list[ idx ]
}Tests
import { nth } from './nth'
test('happy', () => {
expect(nth(2, [ 1, 2, 3, 4 ])).toEqual(3)
})
test('with curry', () => {
expect(nth(2)([ 1, 2, 3, 4 ])).toEqual(3)
})
test('with string', () => {
expect(nth(2)('foo')).toEqual('o')
})
test('with negative index', () => {
expect(nth(-3)([ 1, 2, 3, 4 ])).toEqual(2)
})Typescript test
import {nth} from 'rambda'
const list = [1, 2, 3]
describe('R.nth', () => {
it('happy', () => {
const result = nth(4, list)
result // $ExpectType number | undefined
})
it('curried', () => {
const result = nth(1)(list)
result // $ExpectType number | undefined
})
})of
of<T>(x: T): T[]It returns a partial copy of an obj without propsToOmit properties.
R.of(null); //=> [null]
R.of([42]); //=> [[42]]Try the above R.of example in Rambda REPL
All Typescript definitions
of<T>(x: T): T[];R.of source
export function of(value){
return [ value ]
}Tests
import { of } from './of'
test('happy', () => {
expect(of(3)).toEqual([ 3 ])
expect(of(null)).toEqual([ null ])
})Typescript test
import {of} from 'ramda'
const list = [1, 2, 3]
describe('R.of', () => {
it('happy', () => {
const result = of(4)
result // $ExpectType number[]
})
it('curried', () => {
const result = of(list)
result // $ExpectType number[][]
})
})omit
omit<T, K extends string>(propsToOmit: readonly K[], obj: T): Omit<T, K>It returns a partial copy of an obj without propsToOmit properties.
const obj = {a: 1, b: 2, c: 3}
const propsToOmit = 'a,c,d'
const propsToOmitList = ['a', 'c', 'd']
const result = [
R.omit(propsToOmit, obj),
R.omit(propsToOmitList, obj)
]
// => [{b: 2}, {b: 2}]Try the above R.omit example in Rambda REPL
All Typescript definitions
omit<T, K extends string>(propsToOmit: readonly K[], obj: T): Omit<T, K>;
omit<K extends string>(propsToOmit: readonly K[]): <T>(obj: T) => Omit<T, K>;
omit<T, U>(propsToOmit: string, obj: T): U;
omit<T, U>(propsToOmit: string): (obj: T) => U;
omit<T>(propsToOmit: string, obj: object): T;
omit<T>(propsToOmit: string): (obj: object) => T;R.omit source
export function omit(propsToOmit, obj){
if (arguments.length === 1) return _obj => omit(propsToOmit, _obj)
if (obj === null || obj === undefined){
return undefined
}
const propsToOmitValue =
typeof propsToOmit === 'string' ? propsToOmit.split(',') : propsToOmit
const willReturn = {}
for (const key in obj){
if (!propsToOmitValue.includes(key)){
willReturn[ key ] = obj[ key ]
}
}
return willReturn
}Tests
import { omit } from './omit'
test('with string as condition', () => {
const obj = {
a : 1,
b : 2,
c : 3,
}
const result = omit('a,c', obj)
const resultCurry = omit('a,c')(obj)
const expectedResult = { b : 2 }
expect(result).toEqual(expectedResult)
expect(resultCurry).toEqual(expectedResult)
})
test('with null', () => {
expect(omit('a,b', null)).toEqual(undefined)
})
test('doesn\'t work with number as property', () => {
expect(omit([ 42 ], {
a : 1,
42 : 2,
})).toEqual({
42 : 2,
a : 1,
})
})
test('happy', () => {
expect(omit([ 'a', 'c' ])({
a : 'foo',
b : 'bar',
c : 'baz',
})).toEqual({ b : 'bar' })
})Typescript test
import {omit} from 'rambda'
describe('R.omit with array as props input', () => {
it('allow Typescript to infer object type', () => {
const input = {a: 'foo', b: 2, c: 3, d: 4}
const result = omit(['b,c'], input)
result.a // $ExpectType string
result.d // $ExpectType number
const curriedResult = omit(['a,c'], input)
curriedResult.a // $ExpectType string
curriedResult.d // $ExpectType number
})
it('declare type of input object', () => {
interface Input {
a: string,
b: number,
c: number,
d: number,
}
const input: Input = {a: 'foo', b: 2, c: 3, d: 4}
const result = omit(['b,c'], input)
result // $ExpectType Pick<Input, "b" | "a" | "c" | "d">
result.a // $ExpectType string
result.d // $ExpectType number
const curriedResult = omit(['a,c'], input)
curriedResult.a // $ExpectType string
curriedResult.d // $ExpectType number
})
})
describe('R.omit with string as props input', () => {
interface Output {
b: number,
d: number,
}
it('explicitly declare output', () => {
const result = omit<Output>('a,c', {a: 1, b: 2, c: 3, d: 4})
result // $ExpectType Output
result.b // $ExpectType number
const curriedResult = omit<Output>('a,c')({a: 1, b: 2, c: 3, d: 4})
curriedResult.b // $ExpectType number
})
it('explicitly declare input and output', () => {
interface Input {
a: number,
b: number,
c: number,
d: number,
}
const result = omit<Input, Output>('a,c', {a: 1, b: 2, c: 3, d: 4})
result // $ExpectType Output
result.b // $ExpectType number
const curriedResult = omit<Input, Output>('a,c')({
a: 1,
b: 2,
c: 3,
d: 4,
})
curriedResult.b // $ExpectType number
})
it('without passing type', () => {
const result = omit('a,c', {a: 1, b: 2, c: 3, d: 4})
result // $ExpectType unknown
})
})over
over<T>(lens: Lens, fn: Arity1Fn, value: T): TIt returns a copied Object or Array with modified value received by applying function fn to lens focus.
const headLens = R.lensIndex(0)
R.over(headLens, R.toUpper, ['foo', 'bar', 'baz']) //=> ['FOO', 'bar', 'baz']Try the above R.over example in Rambda REPL
All Typescript definitions
over<T>(lens: Lens, fn: Arity1Fn, value: T): T;
over<T>(lens: Lens, fn: Arity1Fn, value: readonly T[]): T[];
over(lens: Lens, fn: Arity1Fn): <T>(value: T) => T;
over(lens: Lens, fn: Arity1Fn): <T>(value: readonly T[]) => T[];
over(lens: Lens): <T>(fn: Arity1Fn, value: T) => T;
over(lens: Lens): <T>(fn: Arity1Fn, value: readonly T[]) => T[];R.over source
import { curry } from './curry'
const Identity = x => ({
x,
map : fn => Identity(fn(x)),
})
function overFn(
lens, fn, object
){
return lens(x => Identity(fn(x)))(object).x
}
export const over = curry(overFn)partial
partial<V0, V1, T>(fn: (x0: V0, x1: V1) => T, args: [V0]): (x1: V1) => TIt is very similar to R.curry, but you can pass initial arguments when you create the curried function.
R.partial will keep returning a function until all the arguments that the function fn expects are passed.
The name comes from the fact that you partially inject the inputs.
const fn = (title, firstName, lastName) => {
return title + ' ' + firstName + ' ' + lastName + '!'
}
const canPassAnyNumberOfArguments = R.partial(fn, 'Hello')
const ramdaStyle = R.partial(fn, ['Hello'])
const finalFn = canPassAnyNumberOfArguments('Foo')
finalFn('Bar') // => 'Hello, Foo Bar!'Try the above R.partial example in Rambda REPL
All Typescript definitions
partial<V0, V1, T>(fn: (x0: V0, x1: V1) => T, args: [V0]): (x1: V1) => T;
partial<V0, V1, V2, T>(fn: (x0: V0, x1: V1, x2: V2) => T, args: [V0, V1]): (x2: V2) => T;
partial<V0, V1, V2, T>(fn: (x0: V0, x1: V1, x2: V2) => T, args: [V0]): (x1: V1, x2: V2) => T;
partial<V0, V1, V2, V3, T>(fn: (x0: V0, x1: V1, x2: V2, x3: V3) => T, args: [V0, V1, V2]): (x2: V3) => T;
partial<V0, V1, V2, V3, T>(fn: (x0: V0, x1: V1, x2: V2, x3: V3) => T, args: [V0, V1]): (x2: V2, x3: V3) => T;
partial<V0, V1, V2, V3, T>(fn: (x0: V0, x1: V1, x2: V2, x3: V3) => T, args: [V0]): (x1: V1, x2: V2, x3: V3) => T;
partial<T>(fn: (...a: readonly any[]) => T, args: readonly any[]): (...a: readonly any[]) => T;R.partial source
export function partial(fn, ...args){
const len = fn.length
return (...rest) => {
if (args.length + rest.length >= len){
return fn(...args, ...rest)
}
return partial(fn, ...[ ...args, ...rest ])
}
}Tests
import { partial } from './partial'
import { type } from './type'
const greet = (
salutation, title, firstName, lastName
) =>
salutation + ', ' + title + ' ' + firstName + ' ' + lastName + '!'
test('happy', () => {
const canPassAnyNumberOfArguments = partial(
greet, 'Hello', 'Ms.'
)
const fn = canPassAnyNumberOfArguments('foo')
const sayHello = partial(greet, [ 'Hello' ])
const sayHelloRamda = partial(sayHello, [ 'Ms.' ])
expect(type(fn)).toBe('Function')
expect(fn('bar')).toBe('Hello, Ms. foo bar!')
expect(sayHelloRamda('foo', 'bar')).toBe('Hello, Ms. foo bar!')
})
test('extra arguments are ignored', () => {
const canPassAnyNumberOfArguments = partial(
greet, 'Hello', 'Ms.'
)
const fn = canPassAnyNumberOfArguments('foo')
expect(type(fn)).toBe('Function')
expect(fn(
'bar', 1, 2
)).toBe('Hello, Ms. foo bar!')
})
test('when array is input', () => {
const fooFn = (
a, b, c, d
) => ({
a,
b,
c,
d,
})
const barFn = partial(
fooFn, [ 1, 2 ], []
)
expect(barFn(1, 2)).toEqual({
a : [ 1, 2 ],
b : [],
c : 1,
d : 2,
})
})
test('ramda spec', () => {
const sayHello = partial(greet, 'Hello')
const sayHelloToMs = partial(sayHello, 'Ms.')
expect(sayHelloToMs('Jane', 'Jones')).toBe('Hello, Ms. Jane Jones!')
})Typescript test
import {partial} from 'rambda'
describe('R.partial', () => {
it('happy', () => {
function greet(
salutation: string,
title: string,
firstName: string,
lastName: string
) {
return `${salutation}, ${title} ${firstName} ${lastName}!`
}
const sayHello = partial(greet, ['Hello'])
const sayHelloToMs = partial(sayHello, ['Ms.'])
const result = sayHelloToMs('Jane', 'Jones')
result // $ExpectType string
})
})partition
partition<T>(
predicate: Predicatex<T>,
input: T[]
): [T[], T[]]It will return array of two objects/arrays according to predicate function. The first member holds all instanses of input that pass the predicate function, while the second member - those who doesn't.
input can be either an object or an array unlike Ramda where only array is a valid input.
const list = [1, 2, 3]
const obj = {a: 1, b: 2, c: 3}
const predicate = x => x > 2
const result = [
R.partition(predicate, list),
R.partition(predicate, obj)
]
const expected = [
[[3], [1, 2]],
[{c: 3}, {a: 1, b: 2}],
]
// `result` is equal to `expected`Try the above R.partition example in Rambda REPL
All Typescript definitions
partition<T>(
predicate: Predicatex<T>,
input: T[]
): [T[], T[]];
partition<T>(
predicate: Predicatex<T>
): (input: T[]) => [T[], T[]];
partition<T>(
predicate: (x: T, prop?: string) => boolean,
input: { [key: string]: T}
): [{ [key: string]: T}, { [key: string]: T}];
partition<T>(
predicate: (x: T, prop?: string) => boolean
): (input: { [key: string]: T}) => [{ [key: string]: T}, { [key: string]: T}];R.partition source
import { _isArray } from './_internals/_isArray'
function whenObject(predicate, input){
const yes = {}
const no = {}
Object.entries(input).forEach(([ prop, value ]) => {
if (predicate(value, prop)){
yes[ prop ] = value
} else {
no[ prop ] = value
}
})
return [ yes, no ]
}
export function partition(predicate, input){
if (arguments.length === 1){
return listHolder => partition(predicate, listHolder)
}
if (!_isArray(input)) return whenObject(predicate, input)
const yes = []
const no = []
let counter = -1
while (counter++ < input.length - 1){
if (predicate(input[ counter ], counter)){
yes.push(input[ counter ])
} else {
no.push(input[ counter ])
}
}
return [ yes, no ]
}Tests
import { partition } from './partition'
test('with array', () => {
const predicate = (x, i) => {
expect(typeof i).toBe('number')
return x > 2
}
const list = [ 1, 2, 3, 4 ]
const result = partition(predicate, list)
const expectedResult = [
[ 3, 4 ],
[ 1, 2 ],
]
expect(result).toEqual(expectedResult)
})
test('with object', () => {
const predicate = (value, prop) => {
expect(typeof prop).toBe('string')
return value > 2
}
const hash = {
a : 1,
b : 2,
c : 3,
d : 4,
}
const result = partition(predicate)(hash)
const expectedResult = [
{
c : 3,
d : 4,
},
{
a : 1,
b : 2,
},
]
expect(result).toEqual(expectedResult)
})
test('readme example', () => {
const list = [ 1, 2, 3 ]
const obj = {
a : 1,
b : 2,
c : 3,
}
const predicate = x => x > 2
const result = [ partition(predicate, list), partition(predicate, obj) ]
const expected = [
[ [ 3 ], [ 1, 2 ] ],
[
{ c : 3 },
{
a : 1,
b : 2,
},
],
]
expect(result).toEqual(expected)
})Typescript test
import {partition} from 'rambda'
describe('R.partition', () => {
it('with array', () => {
const predicate = (x: number, i: number) => {
return x > 2
}
const list = [1, 2, 3, 4]
const result = partition(predicate, list)
const curriedResult = partition(predicate)(list)
result // $ExpectType [number[], number[]]
curriedResult // $ExpectType [number[], number[]]
})
it('with object', () => {
const predicate = (value: number, prop?: string) => {
return value > 2
}
const hash = {
a: 1,
b: 2,
c: 3,
d: 4,
}
const result = partition(predicate, hash)
const curriedResult = partition(predicate)(hash)
result[0] // $ExpectType { [key: string]: number; }
result[1] // $ExpectType { [key: string]: number; }
curriedResult[0] // $ExpectType { [key: string]: number; }
curriedResult[1] // $ExpectType { [key: string]: number; }
})
})1 failed Ramda.partition specs
💥 Reason for the failure: Ramda library supports fantasy-land
path
path<Input, T>(pathToSearch: string | string[], obj: Input): T | undefinedIf pathToSearch is 'a.b' then it will return 1 if obj is {a:{b:1}}.
It will return undefined, if such path is not found.
const obj = {a: {b: 1}}
const pathToSearch = 'a.b'
const pathToSearchList = ['a', 'b']
const result = [
R.path(pathToSearch, obj),
R.path(pathToSearchList, obj),
R.path('a.b.c.d', obj)
]
// => [1, 1, undefined]Try the above R.path example in Rambda REPL
All Typescript definitions
path<Input, T>(pathToSearch: string | string[], obj: Input): T | undefined;
path<T>(pathToSearch: string | string[], obj: any): T | undefined;
path<T>(pathToSearch: string | string[]): (obj: any) => T | undefined;
path<Input, T>(pathToSearch: string | string[]): (obj: Input) => T | undefined;R.path source
export function path(list, obj){
if (arguments.length === 1) return _obj => path(list, _obj)
if (obj === null || obj === undefined){
return undefined
}
let willReturn = obj
let counter = 0
const pathArrValue = typeof list === 'string' ? list.split('.') : list
while (counter < pathArrValue.length){
if (willReturn === null || willReturn === undefined){
return undefined
}
willReturn = willReturn[ pathArrValue[ counter ] ]
counter++
}
return willReturn
}Tests
import { path } from './path'
test('with array inside object', () => {
const obj = { a : { b : [ 1, { c : 1 } ] } }
expect(path('a.b.1.c', obj)).toBe(1)
})
test('works with undefined', () => {
const obj = { a : { b : { c : 1 } } }
expect(path('a.b.c.d.f', obj)).toBeUndefined()
expect(path('foo.babaz', undefined)).toBeUndefined()
expect(path('foo.babaz')(undefined)).toBeUndefined()
})
test('works with string instead of array', () => {
expect(path('foo.bar.baz')({ foo : { bar : { baz : 'yes' } } })).toEqual('yes')
})
test('path', () => {
expect(path([ 'foo', 'bar', 'baz' ])({ foo : { bar : { baz : 'yes' } } })).toEqual('yes')
expect(path([ 'foo', 'bar', 'baz' ])(null)).toBeUndefined()
expect(path([ 'foo', 'bar', 'baz' ])({ foo : { bar : 'baz' } })).toBeUndefined()
})Typescript test
import {path} from 'rambda'
interface Input {
a: number,
b: {
c: boolean,
},
}
describe('R.path', () => {
it('without specified input type', () => {
const input = {a: 1, b: {c: true}}
const result = path<boolean>('a.b.c', input)
const resultCurried = path<boolean>('a.b.c')(input)
result // $ExpectType boolean | undefined
resultCurried // $ExpectType boolean | undefined
})
it('without specified output type', () => {
const input = {a: 1, b: {c: true}}
const result = path('a.b.c', input)
result // $ExpectType unknown
})
it('with string as path', () => {
const input: Input = {a: 1, b: {c: true}}
const resultA = path<boolean>('a.b.c', input)
const resultB = path<boolean>('a.b.c')(input)
resultA // $ExpectType boolean | undefined
resultB // $ExpectType boolean | undefined
})
it('with array as path', () => {
const input: Input = {a: 1, b: {c: true}}
const resultA = path<boolean>(['a', 'b', 'c'], input)
const resultB = path<boolean>(['a', 'b', 'c'])(input)
resultA // $ExpectType boolean | undefined
resultB // $ExpectType boolean | undefined
})
})
describe('path with specified input', () => {
it('with string as path', () => {
const input: Input = {a: 1, b: {c: true}}
// const wrongInput = { a: 1, b: true }
// const resultA = path<Input, boolean>('a.b.c', wrongInput)
const resultA = path<Input, boolean>('a.b.c', input)
const resultB = path<Input, boolean>('a.b.c')(input)
resultA // $ExpectType boolean | undefined
resultB // $ExpectType boolean | undefined
})
it('with array as path', () => {
const input: Input = {a: 1, b: {c: true}}
const resultA = path<Input, boolean>(['a', 'b', 'c'], input)
const resultB = path<Input, boolean>(['a', 'b', 'c'])(input)
resultA // $ExpectType boolean | undefined
resultB // $ExpectType boolean | undefined
})
})1 failed Ramda.path specs
💥 Reason for the failure: Ramda method supports negative indexes
💥 Reason for the failure: Ramda method supports negative indexes
var R = require('../../../../dist/rambda.js');
var eq = require('./shared/eq');
describe('path', function() {
var deepObject = {a: {b: {c: 'c'}}, falseVal: false, nullVal: null, undefinedVal: undefined, arrayVal: ['arr']};
it('takes a path that contains negative indices into arrays', function() {
eq(R.path(['x', -2], {x: ['a', 'b', 'c', 'd']}), 'c');
eq(R.path([-1, 'y'], [{x: 1, y: 99}, {x: 2, y: 98}, {x: 3, y: 97}]), 97);
});
});pathEq
pathEq(pathToSearch: Path, target: any, input: any): booleanIt returns true if pathToSearch of input object is equal to target value.
pathToSearch is passed to R.path, which means that it can be either a string or an array. Also equality between target and the found value is determined by R.equals.
const path = 'a.b'
const target = {c: 1}
const input = {a: {b: {c: 1}}}
const result = R.pathEq(
path,
target,
input
)
// => trueTry the above R.pathEq example in Rambda REPL
All Typescript definitions
pathEq(pathToSearch: Path, target: any, input: any): boolean;
pathEq(pathToSearch: Path, target: any): (input: any) => boolean;
pathEq(pathToSearch: Path): FunctionToolbelt.Curry<(a: any, b: any) => boolean>;R.pathEq source
import { curry } from './curry'
import { equals } from './equals'
import { path } from './path'
function pathEqFn(
pathToSearch, target, input
){
return equals(path(pathToSearch, input), target)
}
export const pathEq = curry(pathEqFn)Tests
import { pathEq } from './pathEq'
test('when true', () => {
const path = 'a.b'
const obj = { a : { b : { c : 1 } } }
const target = { c : 1 }
expect(pathEq(
path, target, obj
)).toBeTrue()
})
test('when false', () => {
const path = 'a.b'
const obj = { a : { b : 1 } }
const target = 2
expect(pathEq(path, target)(obj)).toBeFalse()
})
test('when wrong path', () => {
const path = 'foo.bar'
const obj = { a : { b : 1 } }
const target = 2
expect(pathEq(
path, target, obj
)).toBeFalse()
})Typescript test
import {pathEq} from 'rambda'
describe('R.pathEq', () => {
it('with string path', () => {
const pathToSearch = 'a.b.c'
const input = {a: {b: {c: 1}}}
const target = {c: 1}
const result = pathEq(pathToSearch, input, target)
const curriedResult = pathEq(pathToSearch, input, target)
result // $ExpectType boolean
curriedResult // $ExpectType boolean
})
it('with array path', () => {
const pathToSearch = ['a', 'b', 'c']
const input = {a: {b: {c: 1}}}
const target = {c: 1}
const result = pathEq(pathToSearch, input, target)
const curriedResult = pathEq(pathToSearch, input, target)
result // $ExpectType boolean
curriedResult // $ExpectType boolean
})
})
describe('with ramda specs', () => {
const testPath = ['x', 0, 'y']
const testObj = {
x: [
{y: 2, z: 3},
{y: 4, z: 5},
],
}
const result1 = pathEq(testPath, 2, testObj)
const result2 = pathEq(testPath, 2)(testObj)
const result3 = pathEq(testPath)(2)(testObj)
const result4 = pathEq(testPath)(2, testObj)
result1 // $ExpectType boolean
result2 // $ExpectType boolean
result3 // $ExpectType boolean
result4 // $ExpectType boolean
})1 failed Ramda.pathEq specs
💥 Reason for the failure: Ramda library supports fantasy-land
pathOr
pathOr<T>(defaultValue: T, pathToSearch: Path, obj: any): TIt reads obj input and returns either R.path(pathToSearch, obj) result or defaultValue input.
const defaultValue = 'DEFAULT_VALUE'
const pathToSearch = 'a.b'
const pathToSearchList = ['a', 'b']
const obj = {
a : {
b : 1
}
}
const result = [
R.pathOr(DEFAULT_VALUE, pathToSearch, obj)
R.pathOr(DEFAULT_VALUE, pathToSearchList, obj)
R.pathOr(DEFAULT_VALUE, 'a.b.c', obj)
]
// => [1, 1, 'DEFAULT_VALUE']Try the above R.pathOr example in Rambda REPL
All Typescript definitions
pathOr<T>(defaultValue: T, pathToSearch: Path, obj: any): T;
pathOr<T>(defaultValue: T, pathToSearch: Path): (obj: any) => T;
pathOr<T>(defaultValue: T): FunctionToolbelt.Curry<(a: Path, b: any) => T>;R.pathOr source
import { curry } from './curry'
import { defaultTo } from './defaultTo'
import { path } from './path'
function pathOrFn(
defaultValue, list, obj
){
return defaultTo(defaultValue, path(list, obj))
}
export const pathOr = curry(pathOrFn)Tests
import { pathOr } from './pathOr'
test('with undefined', () => {
const result = pathOr(
'foo', 'x.y', { x : { y : 1 } }
)
expect(result).toEqual(1)
})
test('with null', () => {
const result = pathOr(
'foo', 'x.y', null
)
expect(result).toEqual('foo')
})
test('with NaN', () => {
const result = pathOr(
'foo', 'x.y', NaN
)
expect(result).toEqual('foo')
})
test('curry case (x)(y)(z)', () => {
const result = pathOr('foo')('x.y.z')({ x : { y : { a : 1 } } })
expect(result).toEqual('foo')
})
test('curry case (x)(y,z)', () => {
const result = pathOr('foo', 'x.y.z')({ x : { y : { a : 1 } } })
expect(result).toEqual('foo')
})
test('curry case (x,y)(z)', () => {
const result = pathOr('foo')('x.y.z', { x : { y : { a : 1 } } })
expect(result).toEqual('foo')
})Typescript test
import {pathOr} from 'rambda'
describe('R.pathOr', () => {
it('with string path', () => {
const x = pathOr<string>('foo', 'x.y', {x: {y: 'bar'}})
x // $ExpectType string
})
it('with array path', () => {
const x = pathOr<string>('foo', ['x', 'y'], {x: {y: 'bar'}})
x // $ExpectType string
})
it('without passing type looks bad', () => {
const x = pathOr('foo', 'x.y', {x: {y: 'bar'}})
x // $ExpectType "foo"
})
it('curried', () => {
const x = pathOr<string>('foo', 'x.y')({x: {y: 'bar'}})
x // $ExpectType string
})
})paths
paths<Input, T>(pathsToSearch: Path[], obj: Input): (T | undefined)[]It loops over members of pathsToSearch as singlePath and returns the array produced by R.path(singlePath, obj).
Because it calls R.path, then singlePath can be either string or a list.
const obj = {
a : {
b : {
c : 1,
d : 2
}
}
}
const result = R.paths([
'a.b.c',
'a.b.c.d',
'a.b.c.d.e',
], obj)
// => [1, 2, undefined]Try the above R.paths example in Rambda REPL
All Typescript definitions
paths<Input, T>(pathsToSearch: Path[], obj: Input): (T | undefined)[];
paths<Input, T>(pathsToSearch: Path[]): (obj: Input) => (T | undefined)[];
paths<T>(pathsToSearch: Path[], obj: any): (T | undefined)[];
paths<T>(pathsToSearch: Path[]): (obj: any) => (T | undefined)[];R.paths source
import { path } from './path'
export function paths(pathsToSearch, obj){
if (arguments.length === 1){
return _obj => paths(pathsToSearch, _obj)
}
return pathsToSearch.map(singlePath => path(singlePath, obj))
}Tests
import { paths } from './paths'
const obj = {
a : {
b : {
c : 1,
d : 2,
},
},
p : [ { q : 3 }, 'Hi' ],
x : {
y : 'Alice',
z : [ [ {} ] ],
},
}
test('with string path + curry', () => {
const pathsInput = [ 'a.b.d', 'p.q' ]
const expected = [ 2, undefined ]
const result = paths(pathsInput, obj)
const curriedResult = paths(pathsInput)(obj)
expect(result).toEqual(expected)
expect(curriedResult).toEqual(expected)
})
test('with array path', () => {
const result = paths([
[ 'a', 'b', 'c' ],
[ 'x', 'y' ],
],
obj)
expect(result).toEqual([ 1, 'Alice' ])
})
test('takes a paths that contains indices into arrays', () => {
expect(paths([
[ 'p', 0, 'q' ],
[ 'x', 'z', 0, 0 ],
],
obj)).toEqual([ 3, {} ])
expect(paths([
[ 'p', 0, 'q' ],
[ 'x', 'z', 2, 1 ],
],
obj)).toEqual([ 3, undefined ])
})
test('gets a deep property\'s value from objects', () => {
expect(paths([ [ 'a', 'b' ] ], obj)).toEqual([ obj.a.b ])
expect(paths([ [ 'p', 0 ] ], obj)).toEqual([ obj.p[ 0 ] ])
})
test('returns undefined for items not found', () => {
expect(paths([ [ 'a', 'x', 'y' ] ], obj)).toEqual([ undefined ])
expect(paths([ [ 'p', 2 ] ], obj)).toEqual([ undefined ])
})Typescript test
import {paths} from 'rambda'
interface Input {
a: number,
b: number,
c: number,
}
const input: Input = {a: 1, b: 2, c: 3}
describe('R.paths', () => {
it('with dot notation', () => {
const result = paths<number>(['a.b.c', 'foo.bar'], input)
result // $ExpectType (number | undefined)[]
})
it('without type', () => {
const result = paths(['a.b.c', 'foo.bar'], input)
result // $ExpectType unknown[]
})
it('with array as path', () => {
const result = paths<number>([['a', 'b', 'c'], ['foo.bar']], input)
result // $ExpectType (number | undefined)[]
})
it('curried', () => {
const result = paths<number>([['a', 'b', 'c'], ['foo.bar']])(input)
result // $ExpectType (number | undefined)[]
})
})1 failed Ramda.paths specs
💥 Reason for the failure: Ramda method supports negative indexes
💥 Reason for the failure: Ramda method supports negative indexes
var R = require('../../../../dist/rambda.js');
var eq = require('./shared/eq');
describe('paths', function() {
var obj = {
a: {
b: {
c: 1,
d: 2
}
},
p: [{q: 3}, 'Hi'],
x: {
y: 'Alice',
z: [[{}]]
}
};
it('takes a path that contains negative indices into arrays', function() {
eq(R.paths([['p', -2, 'q'], ['p', -1]], obj), [3, 'Hi']);
eq(R.paths([['p', -4, 'q'], ['x', 'z', -1, 0]], obj), [undefined, {}]);
});
});pick
pick<T, K extends string | number | symbol>(propsToPick: readonly K[], input: T): Pick<T, Exclude<keyof T, Exclude<keyof T, K>>>It returns a partial copy of an input containing only propsToPick properties.
input can be either an object or an array.
String anotation of propsToPick is one of the differences between Rambda and Ramda.
const obj = {
a : 1,
b : false,
foo: 'cherry'
}
const list = [1, 2, 3, 4]
const propsToPick = 'a,foo'
const propsToPickList = ['a', 'foo']
const result = [
R.pick(propsToPick, obj),
R.pick(propsToPickList, obj),
R.pick('a,bar', obj),
R.pick('bar', obj),
R.pick([0, 3], list),
R.pick('0,3', list),
]
const expected = [
{a:1, foo: 'cherry'},
{a:1, foo: 'cherry'},
{a:1},
{},
[1,4],
[1,4]
]
// => `result` is equal to `expected`Try the above R.pick example in Rambda REPL
All Typescript definitions
pick<T, K extends string | number | symbol>(propsToPick: readonly K[], input: T): Pick<T, Exclude<keyof T, Exclude<keyof T, K>>>;
pick<K extends string | number | symbol>(propsToPick: readonly K[]): <T>(input: T) => Pick<T, Exclude<keyof T, Exclude<keyof T, K>>>;
pick<T, U>(propsToPick: string, input: T): U;
pick<T, U>(propsToPick: string): (input: T) => U;
pick<T>(propsToPick: string, input: object): T;
pick<T>(propsToPick: string): (input: object) => T;R.pick source
export function pick(propsToPick, input){
if (arguments.length === 1) return _input => pick(propsToPick, _input)
if (input === null || input === undefined){
return undefined
}
const keys =
typeof propsToPick === 'string' ? propsToPick.split(',') : propsToPick
const willReturn = {}
let counter = 0
while (counter < keys.length){
if (keys[ counter ] in input){
willReturn[ keys[ counter ] ] = input[ keys[ counter ] ]
}
counter++
}
return willReturn
}Tests
import { pick } from './pick'
const obj = {
a : 1,
b : 2,
c : 3,
}
test('props to pick is a string', () => {
const result = pick('a,c', obj)
const resultCurry = pick('a,c')(obj)
const expectedResult = {
a : 1,
c : 3,
}
expect(result).toEqual(expectedResult)
expect(resultCurry).toEqual(expectedResult)
})
test('when prop is missing', () => {
const result = pick('a,d,f', obj)
expect(result).toEqual({ a : 1 })
})
test('props to pick is an array', () => {
expect(pick([ 'a', 'c' ])({
a : 'foo',
b : 'bar',
c : 'baz',
})).toEqual({
a : 'foo',
c : 'baz',
})
expect(pick([ 'a', 'd', 'e', 'f' ])({
a : 'foo',
b : 'bar',
c : 'baz',
})).toEqual({ a : 'foo' })
expect(pick('a,d,e,f')(null)).toEqual(undefined)
})
test('works with list as input and number as props - props to pick is an array', () => {
const result = pick([ 1, 2 ], [ 'a', 'b', 'c', 'd' ])
expect(result).toEqual({
1 : 'b',
2 : 'c',
})
})
test('works with list as input and number as props - props to pick is a string', () => {
const result = pick('1,2', [ 'a', 'b', 'c', 'd' ])
expect(result).toEqual({
1 : 'b',
2 : 'c',
})
})
test('with symbol', () => {
const symbolProp = Symbol('s')
expect(pick([ symbolProp ], { [ symbolProp ] : 'a' })).toMatchInlineSnapshot(`
Object {
Symbol(s): "a",
}
`)
})Typescript test
import {pick} from 'rambda'
const input = {a: 'foo', b: 2, c: 3, d: 4}
describe('R.pick with array as props input', () => {
it('without passing type', () => {
const result = pick(['a', 'c'], input)
result.a // $ExpectType string
result.c // $ExpectType number
})
})
describe('R.pick with string as props input', () => {
interface Input {
a: string,
b: number,
c: number,
d: number,
}
interface Output {
a: string,
c: number,
}
it('explicitly declare output', () => {
const result = pick<Output>('a,c', input)
result // $ExpectType Output
result.a // $ExpectType string
result.c // $ExpectType number
const curriedResult = pick<Output>('a,c')(input)
curriedResult.a // $ExpectType string
})
it('explicitly declare input and output', () => {
const result = pick<Input, Output>('a,c', input)
result // $ExpectType Output
result.a // $ExpectType string
const curriedResult = pick<Input, Output>('a,c')(input)
curriedResult.a // $ExpectType string
})
it('without passing type', () => {
const result = pick('a,c', input)
result // $ExpectType unknown
})
})pickAll
pickAll<T, U>(propsToPick: readonly string[], input: T): USame as R.pick but it won't skip the missing props, i.e. it will assign them to undefined.
const obj = {
a : 1,
b : false,
foo: 'cherry'
}
const propsToPick = 'a,foo,bar'
const propsToPickList = ['a', 'foo', 'bar']
const result = [
R.pickAll(propsToPick, obj),
R.pickAll(propsToPickList, obj),
R.pickAll('a,bar', obj),
R.pickAll('bar', obj),
]
const expected = [
{a:1, foo: 'cherry', bar: undefined},
{a:1, foo: 'cherry', bar: undefined},
{a:1, bar: undefined},
{bar: undefined}
]
// => `result` is equal to `expected`Try the above R.pickAll example in Rambda REPL
All Typescript definitions
pickAll<T, U>(propsToPick: readonly string[], input: T): U;
pickAll<T, U>(propsToPick: readonly string[]): (input: T) => U;
pickAll<T, U>(propsToPick: string, input: T): U;
pickAll<T, U>(propsToPick: string): (input: T) => U;R.pickAll source
export function pickAll(propsToPick, obj){
if (arguments.length === 1) return _obj => pickAll(propsToPick, _obj)
if (obj === null || obj === undefined){
return undefined
}
const keysValue =
typeof propsToPick === 'string' ? propsToPick.split(',') : propsToPick
const willReturn = {}
let counter = 0
while (counter < keysValue.length){
if (keysValue[ counter ] in obj){
willReturn[ keysValue[ counter ] ] = obj[ keysValue[ counter ] ]
} else {
willReturn[ keysValue[ counter ] ] = undefined
}
counter++
}
return willReturn
}Tests
import { pickAll } from './pickAll'
test('when input is undefined or null', () => {
expect(pickAll('a', null)).toBe(undefined)
expect(pickAll('a', undefined)).toBe(undefined)
})
test('with string as condition', () => {
const obj = {
a : 1,
b : 2,
c : 3,
}
const result = pickAll('a,c', obj)
const resultCurry = pickAll('a,c')(obj)
const expectedResult = {
a : 1,
b : undefined,
c : 3,
}
expect(result).toEqual(expectedResult)
expect(resultCurry).toEqual(expectedResult)
})
test('with array as condition', () => {
expect(pickAll([ 'a', 'b', 'c' ], {
a : 'foo',
c : 'baz',
})).toEqual({
a : 'foo',
b : undefined,
c : 'baz',
})
})Typescript test
import {pickAll} from 'rambda'
interface Input {
a: string,
b: number,
c: number,
d: number,
}
interface Output {
a?: string,
c?: number,
}
const input = {a: 'foo', b: 2, c: 3, d: 4}
describe('R.pickAll with array as props input', () => {
it('without passing type', () => {
const result = pickAll(['a', 'c'], input)
result // $ExpectType unknown
})
it('without passing type + curry', () => {
const result = pickAll(['a', 'c'])(input)
result // $ExpectType unknown
})
it('explicitly passing types', () => {
const result = pickAll<Input, Output>(['a', 'c'], input)
result.a // $ExpectType string | undefined
result.c // $ExpectType number | undefined
})
it('explicitly passing types + curry', () => {
const result = pickAll<Input, Output>(['a', 'c'])(input)
result.a // $ExpectType string | undefined
result.c // $ExpectType number | undefined
})
})
describe('R.pickAll with string as props input', () => {
it('without passing type', () => {
const result = pickAll('a,c', input)
result // $ExpectType unknown
})
it('without passing type + curry', () => {
const result = pickAll('a,c')(input)
result // $ExpectType unknown
})
it('explicitly passing types', () => {
const result = pickAll<Input, Output>('a,c', input)
result.a // $ExpectType string | undefined
result.c // $ExpectType number | undefined
})
it('explicitly passing types + curry', () => {
const result = pickAll<Input, Output>('a,c')(input)
result.a // $ExpectType string | undefined
result.c // $ExpectType number | undefined
})
})pipe
pipe<T1>(fn0: () => T1): () => T1It performs left-to-right function composition.
const result = R.pipe(
R.filter(val => val > 2),
R.map(a => a * 2)
)([1, 2, 3, 4])
// => [6, 8]Try the above R.pipe example in Rambda REPL
All Typescript definitions
pipe<T1>(fn0: () => T1): () => T1;
pipe<V0, T1>(fn0: (x0: V0) => T1): (x0: V0) => T1;
pipe<V0, V1, T1>(fn0: (x0: V0, x1: V1) => T1): (x0: V0, x1: V1) => T1;
pipe<V0, V1, V2, T1>(fn0: (x0: V0, x1: V1, x2: V2) => T1): (x0: V0, x1: V1, x2: V2) => T1;
pipe<T1, T2>(fn0: () => T1, fn1: (x: T1) => T2): () => T2;
pipe<V0, T1, T2>(fn0: (x0: V0) => T1, fn1: (x: T1) => T2): (x0: V0) => T2;
pipe<V0, V1, T1, T2>(fn0: (x0: V0, x1: V1) => T1, fn1: (x: T1) => T2): (x0: V0, x1: V1) => T2;
pipe<V0, V1, V2, T1, T2>(fn0: (x0: V0, x1: V1, x2: V2) => T1, fn1: (x: T1) => T2): (x0: V0, x1: V1, x2: V2) => T2;
pipe<T1, T2, T3>(fn0: () => T1, fn1: (x: T1) => T2, fn2: (x: T2) => T3): () => T3;
pipe<V0, T1, T2, T3>(fn0: (x: V0) => T1, fn1: (x: T1) => T2, fn2: (x: T2) => T3): (x: V0) => T3;
pipe<V0, V1, T1, T2, T3>(fn0: (x0: V0, x1: V1) => T1, fn1: (x: T1) => T2, fn2: (x: T2) => T3): (x0: V0, x1: V1) => T3;
pipe<V0, V1, V2, T1, T2, T3>(fn0: (x0: V0, x1: V1, x2: V2) => T1, fn1: (x: T1) => T2, fn2: (x: T2) => T3): (x0: V0, x1: V1, x2: V2) => T3;
pipe<T1, T2, T3, T4>(fn0: () => T1, fn1: (x: T1) => T2, fn2: (x: T2) => T3, fn3: (x: T3) => T4): () => T4;
pipe<V0, T1, T2, T3, T4>(fn0: (x: V0) => T1, fn1: (x: T1) => T2, fn2: (x: T2) => T3, fn3: (x: T3) => T4): (x: V0) => T4;
pipe<V0, V1, T1, T2, T3, T4>(fn0: (x0: V0, x1: V1) => T1, fn1: (x: T1) => T2, fn2: (x: T2) => T3, fn3: (x: T3) => T4): (x0: V0, x1: V1) => T4;
pipe<V0, V1, V2, T1, T2, T3, T4>(fn0: (x0: V0, x1: V1, x2: V2) => T1, fn1: (x: T1) => T2, fn2: (x: T2) => T3, fn3: (x: T3) => T4): (x0: V0, x1: V1, x2: V2) => T4;
pipe<T1, T2, T3, T4, T5>(fn0: () => T1, fn1: (x: T1) => T2, fn2: (x: T2) => T3, fn3: (x: T3) => T4, fn4: (x: T4) => T5): () => T5;
pipe<V0, T1, T2, T3, T4, T5>(fn0: (x: V0) => T1, fn1: (x: T1) => T2, fn2: (x: T2) => T3, fn3: (x: T3) => T4, fn4: (x: T4) => T5): (x: V0) => T5;
pipe<V0, V1, T1, T2, T3, T4, T5>(fn0: (x0: V0, x1: V1) => T1, fn1: (x: T1) => T2, fn2: (x: T2) => T3, fn3: (x: T3) => T4, fn4: (x: T4) => T5): (x0: V0, x1: V1) => T5;
pipe<V0, V1, V2, T1, T2, T3, T4, T5>(fn0: (x0: V0, x1: V1, x2: V2) => T1, fn1: (x: T1) => T2, fn2: (x: T2) => T3, fn3: (x: T3) => T4, fn4: (x: T4) => T5): (x0: V0, x1: V1, x2: V2) => T5;
pipe<T1, T2, T3, T4, T5, T6>(fn0: () => T1, fn1: (x: T1) => T2, fn2: (x: T2) => T3, fn3: (x: T3) => T4, fn4: (x: T4) => T5, fn5: (x: T5) => T6): () => T6;
pipe<V0, T1, T2, T3, T4, T5, T6>(fn0: (x: V0) => T1, fn1: (x: T1) => T2, fn2: (x: T2) => T3, fn3: (x: T3) => T4, fn4: (x: T4) => T5, fn5: (x: T5) => T6): (x: V0) => T6;
pipe<V0, V1, T1, T2, T3, T4, T5, T6>(fn0: (x0: V0, x1: V1) => T1, fn1: (x: T1) => T2, fn2: (x: T2) => T3, fn3: (x: T3) => T4, fn4: (x: T4) => T5, fn5: (x: T5) => T6): (x0: V0, x1: V1) => T6;
pipe<V0, V1, V2, T1, T2, T3, T4, T5, T6>(
fn0: (x0: V0, x1: V1, x2: V2) => T1,
fn1: (x: T1) => T2,
fn2: (x: T2) => T3,
fn3: (x: T3) => T4,
fn4: (x: T4) => T5,
fn5: (x: T5) => T6): (x0: V0, x1: V1, x2: V2) => T6;
pipe<T1, T2, T3, T4, T5, T6, T7>(
fn0: () => T1,
fn1: (x: T1) => T2,
fn2: (x: T2) => T3,
fn3: (x: T3) => T4,
fn4: (x: T4) => T5,
fn5: (x: T5) => T6,
fn: (x: T6) => T7): () => T7;
pipe<V0, T1, T2, T3, T4, T5, T6, T7>(
fn0: (x: V0) => T1,
fn1: (x: T1) => T2,
fn2: (x: T2) => T3,
fn3: (x: T3) => T4,
fn4: (x: T4) => T5,
fn5: (x: T5) => T6,
fn: (x: T6) => T7): (x: V0) => T7;
pipe<V0, V1, T1, T2, T3, T4, T5, T6, T7>(
fn0: (x0: V0, x1: V1) => T1,
fn1: (x: T1) => T2,
fn2: (x: T2) => T3,
fn3: (x: T3) => T4,
fn4: (x: T4) => T5,
fn5: (x: T5) => T6,
fn6: (x: T6) => T7): (x0: V0, x1: V1) => T7;
pipe<V0, V1, V2, T1, T2, T3, T4, T5, T6, T7>(
fn0: (x0: V0, x1: V1, x2: V2) => T1,
fn1: (x: T1) => T2,
fn2: (x: T2) => T3,
fn3: (x: T3) => T4,
fn4: (x: T4) => T5,
fn5: (x: T5) => T6,
fn6: (x: T6) => T7): (x0: V0, x1: V1, x2: V2) => T7;
pipe<T1, T2, T3, T4, T5, T6, T7, T8>(
fn0: () => T1,
fn1: (x: T1) => T2,
fn2: (x: T2) => T3,
fn3: (x: T3) => T4,
fn4: (x: T4) => T5,
fn5: (x: T5) => T6,
fn6: (x: T6) => T7,
fn: (x: T7) => T8): () => T8;
pipe<V0, T1, T2, T3, T4, T5, T6, T7, T8>(
fn0: (x: V0) => T1,
fn1: (x: T1) => T2,
fn2: (x: T2) => T3,
fn3: (x: T3) => T4,
fn4: (x: T4) => T5,
fn5: (x: T5) => T6,
fn6: (x: T6) => T7,
fn: (x: T7) => T8): (x: V0) => T8;
pipe<V0, V1, T1, T2, T3, T4, T5, T6, T7, T8>(
fn0: (x0: V0, x1: V1) => T1,
fn1: (x: T1) => T2,
fn2: (x: T2) => T3,
fn3: (x: T3) => T4,
fn4: (x: T4) => T5,
fn5: (x: T5) => T6,
fn6: (x: T6) => T7,
fn7: (x: T7) => T8): (x0: V0, x1: V1) => T8;
pipe<V0, V1, V2, T1, T2, T3, T4, T5, T6, T7, T8>(
fn0: (x0: V0, x1: V1, x2: V2) => T1,
fn1: (x: T1) => T2,
fn2: (x: T2) => T3,
fn3: (x: T3) => T4,
fn4: (x: T4) => T5,
fn5: (x: T5) => T6,
fn6: (x: T6) => T7,
fn7: (x: T7) => T8): (x0: V0, x1: V1, x2: V2) => T8;
pipe<T1, T2, T3, T4, T5, T6, T7, T8, T9>(
fn0: () => T1,
fn1: (x: T1) => T2,
fn2: (x: T2) => T3,
fn3: (x: T3) => T4,
fn4: (x: T4) => T5,
fn5: (x: T5) => T6,
fn6: (x: T6) => T7,
fn7: (x: T7) => T8,
fn8: (x: T8) => T9): () => T9;
pipe<V0, T1, T2, T3, T4, T5, T6, T7, T8, T9>(
fn0: (x0: V0) => T1,
fn1: (x: T1) => T2,
fn2: (x: T2) => T3,
fn3: (x: T3) => T4,
fn4: (x: T4) => T5,
fn5: (x: T5) => T6,
fn6: (x: T6) => T7,
fn7: (x: T7) => T8,
fn8: (x: T8) => T9): (x0: V0) => T9;
pipe<V0, V1, T1, T2, T3, T4, T5, T6, T7, T8, T9>(
fn0: (x0: V0, x1: V1) => T1,
fn1: (x: T1) => T2,
fn2: (x: T2) => T3,
fn3: (x: T3) => T4,
fn4: (x: T4) => T5,
fn5: (x: T5) => T6,
fn6: (x: T6) => T7,
fn7: (x: T7) => T8,
fn8: (x: T8) => T9): (x0: V0, x1: V1) => T9;
pipe<V0, V1, V2, T1, T2, T3, T4, T5, T6, T7, T8, T9>(
fn0: (x0: V0, x1: V1, x2: V2) => T1,
fn1: (x: T1) => T2,
fn2: (x: T2) => T3,
fn3: (x: T3) => T4,
fn4: (x: T4) => T5,
fn5: (x: T5) => T6,
fn6: (x: T6) => T7,
fn7: (x: T7) => T8,
fn8: (x: T8) => T9): (x0: V0, x1: V1, x2: V2) => T9;
pipe<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10>(
fn0: () => T1,
fn1: (x: T1) => T2,
fn2: (x: T2) => T3,
fn3: (x: T3) => T4,
fn4: (x: T4) => T5,
fn5: (x: T5) => T6,
fn6: (x: T6) => T7,
fn7: (x: T7) => T8,
fn8: (x: T8) => T9,
fn9: (x: T9) => T10): () => T10;
pipe<V0, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10>(
fn0: (x0: V0) => T1,
fn1: (x: T1) => T2,
fn2: (x: T2) => T3,
fn3: (x: T3) => T4,
fn4: (x: T4) => T5,
fn5: (x: T5) => T6,
fn6: (x: T6) => T7,
fn7: (x: T7) => T8,
fn8: (x: T8) => T9,
fn9: (x: T9) => T10): (x0: V0) => T10;
pipe<V0, V1, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10>(
fn0: (x0: V0, x1: V1) => T1,
fn1: (x: T1) => T2,
fn2: (x: T2) => T3,
fn3: (x: T3) => T4,
fn4: (x: T4) => T5,
fn5: (x: T5) => T6,
fn6: (x: T6) => T7,
fn7: (x: T7) => T8,
fn8: (x: T8) => T9,
fn9: (x: T9) => T10): (x0: V0, x1: V1) => T10;
pipe<V0, V1, V2, T1, T2, T3, T4, T5, T6, T7, T8, T9, T10>(
fn0: (x0: V0, x1: V1, x2: V2) => T1,
fn1: (x: T1) => T2,
fn2: (x: T2) => T3,
fn3: (x: T3) => T4,
fn4: (x: T4) => T5,
fn5: (x: T5) => T6,
fn6: (x: T6) => T7,
fn7: (x: T7) => T8,
fn8: (x: T8) => T9,
fn9: (x: T9) => T10): (x0: V0, x1: V1, x2: V2) => T10;R.pipe source
import { compose } from './compose'
export function pipe(...fns){
if (fns.length === 0)
throw new Error('pipe requires at least one argument')
return compose(...fns.reverse())
}Tests
import { add, last, map } from '../rambda'
import { pipe } from './pipe'
test('happy', () => {
const list = [ 1, 2, 3 ]
const result = pipe(
map(add(1)), map(add(10)), last
)(list)
expect(result).toEqual(14)
})
test('with bad input', () => {
expect(() => pipe()).toThrowWithMessage(Error,
'pipe requires at least one argument')
})Typescript test
import {add, subtract, pipe} from 'rambda'
describe('R.pipe', () => {
it('happy', () => {
const result = pipe(subtract(11), add(1), add(1))(1)
result // $ExpectType number
})
it('with void', () => {
const result = pipe(
() => {},
() => {}
)()
result // $ExpectType void
})
})3 failed Ramda.pipe specs
💥 Reason for the failure: Ramda method passes context to functions | Rambda composed functions have no length
💥 Reason for the failure: Ramda method passes context to functions | Rambda composed functions have no length
var assert = require('assert');
var R = require('../../../../dist/rambda.js');
var eq = require('./shared/eq');
describe('pipe', function() {
it('performs left-to-right function composition', function() {
// f :: (String, Number?) -> ([Number] -> [Number])
var f = R.pipe(parseInt, R.multiply, R.map);
eq(f.length, 2);
eq(f('10')([1, 2, 3]), [10, 20, 30]);
eq(f('10', 2)([1, 2, 3]), [2, 4, 6]);
});
it('passes context to functions', function() {
function x(val) {
return this.x * val;
}
function y(val) {
return this.y * val;
}
function z(val) {
return this.z * val;
}
var context = {
a: R.pipe(x, y, z),
x: 4,
y: 2,
z: 1
};
eq(context.a(5), 40);
});
it('can be applied to one argument', function() {
var f = function(a, b, c) { return [a, b, c]; };
var g = R.pipe(f);
eq(g.length, 3);
eq(g(1, 2, 3), [1, 2, 3]);
});
});pluck
pluck<T>(property: number, list: ReadonlyArray<T>): TIt returns list of the values of property taken from the all objects inside list.
const list = [{a: 1}, {a: 2}, {b: 3}]
const property = 'a'
R.pluck(list, property)
// => [1, 2]Try the above R.pluck example in Rambda REPL
All Typescript definitions
pluck<T>(property: number, list: ReadonlyArray<T>): T;
pluck<K extends keyof T, T>(property: K, list: ReadonlyArray<T>): T[K][];
pluck(property: number): <T>(list: ReadonlyArray<T>) => T;
pluck<P extends string>(property: P): <T>(list: ReadonlyArray<Record<P, T>>) => T[];R.pluck source
import { map } from './map'
export function pluck(property, list){
if (arguments.length === 1) return _list => pluck(property, _list)
const willReturn = []
map(x => {
if (x[ property ] !== undefined){
willReturn.push(x[ property ])
}
}, list)
return willReturn
}Tests
import { pluck } from './pluck'
test('happy', () => {
expect(pluck('a')([ { a : 1 }, { a : 2 }, { b : 1 } ])).toEqual([ 1, 2 ])
})
test('with number', () => {
const input = [
[ 1, 2 ],
[ 3, 4 ],
]
expect(pluck(0, input)).toEqual([ 1, 3 ])
})Typescript test
import {pluck} from 'rambda'
describe('R.pluck', () => {
it('with object', () => {
interface ListMember {
a: number,
b: string,
}
const input: ListMember[] = [
{a: 1, b: 'foo'},
{a: 2, b: 'bar'},
]
const resultA = pluck('a', input)
const resultB = pluck('b')(input)
resultA // $ExpectType number[]
resultB // $ExpectType string[]
})
it('with array', () => {
const input = [
[1, 2],
[3, 4],
[5, 6],
]
const result = pluck(0, input)
const resultCurry = pluck(0)(input)
result // $ExpectType number[]
resultCurry // $ExpectType number[]
})
})1 failed Ramda.pluck specs
💥 Reason for the failure: Ramda method behaves as a transducer
💥 Reason for the failure: Ramda method behaves as a transducer
var R = require('../../../../dist/rambda.js');
var eq = require('./shared/eq');
describe('pluck', function() {
var people = [
{name: 'Fred', age: 23},
{name: 'Wilma', age: 21},
{name: 'Pebbles', age: 2}
];
it('behaves as a transducer when given a transducer in list position', function() {
var numbers = [{a: 1}, {a: 2}, {a: 3}, {a: 4}];
var transducer = R.compose(R.pluck('a'), R.map(R.add(1)), R.take(2));
eq(R.transduce(transducer, R.flip(R.append), [], numbers), [2, 3]);
});
});prepend
prepend<T>(x: T, listOrString: ReadonlyArray<T>): T[]It adds element x at the beginning of listOrString.
const x = 'foo'
const result = [
R.prepend(x, '_cherry'),
R.prepend(x, ['bar', 'baz'])
]
// => ['foo_cherry', ['foo', 'bar', 'baz']]Try the above R.prepend example in Rambda REPL
All Typescript definitions
prepend<T>(x: T, listOrString: ReadonlyArray<T>): T[];
prepend<T>(x: T): (listOrString: ReadonlyArray<T>) => T[];R.prepend source
export function prepend(x, listOrString){
if (arguments.length === 1)
return _listOrString => prepend(x, _listOrString)
if (typeof listOrString === 'string') return `${ x }${ listOrString }`
return [ x ].concat(listOrString)
}Tests
import { prepend } from './prepend'
test('happy', () => {
expect(prepend('f', 'oo')).toEqual('foo')
})
test('prepend', () => {
expect(prepend('yes', [ 'foo', 'bar', 'baz' ])).toEqual([
'yes',
'foo',
'bar',
'baz',
])
expect(prepend('foo')([])).toEqual([ 'foo' ])
})Typescript test
import {prepend} from 'rambda'
const list = [1, 2, 3]
describe('R.prepend', () => {
it('happy', () => {
const result = prepend(4, list)
result // $ExpectType number[]
})
it('curried', () => {
const result = prepend(4)(list)
result // $ExpectType number[]
})
})product
product(list: ReadonlyArray<number>): numberR.product([ 2, 3, 4 ])
// => 24)Try the above R.product example in Rambda REPL
All Typescript definitions
product(list: ReadonlyArray<number>): number;R.product source
import { multiply } from './multiply'
import { reduce } from './reduce'
export const product = reduce(multiply, 1)Tests
import { product } from './product'
test('happy', () => {
expect(product([ 2, 3, 4 ])).toEqual(24)
})
test('bad input', () => {
expect(product([ null ])).toEqual(0)
expect(product([])).toEqual(1)
})Typescript test
import {product} from 'rambda'
describe('R.product', () => {
it('happy', () => {
const result = product([1, 2, 3])
result // $ExpectType number
})
})prop
prop<P extends keyof T, T>(propToFind: P, obj: T): T[P]It returns the value of property propToFind in obj.
If there is no such property, it returns undefined.
const result = [
R.prop('x', {x: 100}),
R.prop('x', {a: 1})
]
// => [100, undefined]Try the above R.prop example in Rambda REPL
All Typescript definitions
prop<P extends keyof T, T>(propToFind: P, obj: T): T[P];
prop<P extends string>(p: P): <T>(propToFind: Record<P, T>) => T;
prop<P extends string, T>(p: P): (propToFind: Record<P, T>) => T;R.prop source
export function prop(propToFind, obj){
if (arguments.length === 1) return _obj => prop(propToFind, _obj)
if (!obj) return undefined
return obj[ propToFind ]
}Tests
import { prop } from './prop'
test('prop', () => {
expect(prop('foo')({ foo : 'baz' })).toEqual('baz')
expect(prop('bar')({ foo : 'baz' })).toEqual(undefined)
expect(prop('bar')(null)).toEqual(undefined)
})Typescript test
import {prop} from 'rambda'
const obj = {a: 1, b: 'foo'}
describe('R.prop', () => {
it('happy', () => {
const result = prop('a', obj)
result // $ExpectType number
})
it('curried', () => {
const result = prop('b')(obj)
result // $ExpectType string
})
})propEq
propEq<T, K extends keyof T>(propToFind: K, valueToMatch: T[K], obj: T): booleanIt returns true if obj has property propToFind and its value is equal to valueToMatch.
const obj = { foo: 'bar' }
const secondObj = { foo: 1 }
const propToFind = 'foo'
const valueToMatch = 'bar'
const result = [
R.propEq(propToFind, valueToMatch, obj),
R.propEq(propToFind, valueToMatch, secondObj)
]
// => [true, false]Try the above R.propEq example in Rambda REPL
All Typescript definitions
propEq<T, K extends keyof T>(propToFind: K, valueToMatch: T[K], obj: T): boolean;
propEq<T, K extends keyof T>(propToFind: K, valueToMatch: T[K]): (obj: T) => boolean;
propEq<T, K extends keyof T>(propToFind: K): {
(valueToMatch: T[K], obj: T): boolean;
(valueToMatch: T[K]): (obj: T) => boolean;
};R.propEq source
import { curry } from './curry'
function propEqFn(
propToFind, valueToMatch, obj
){
if (!obj) return false
return obj[ propToFind ] === valueToMatch
}
export const propEq = curry(propEqFn)Tests
import { propEq } from './propEq'
test('happy', () => {
expect(propEq('foo', 'bar')({ foo : 'bar' })).toBeTrue()
expect(propEq('foo', 'bar')({ foo : 'baz' })).toBeFalse()
expect(propEq('foo')('bar')({ foo : 'baz' })).toBeFalse()
expect(propEq(
'foo', 'bar', null
)).toBeFalse()
})Typescript test
import {propEq} from 'rambda'
const property = 'foo'
const numberProperty = 1
const value = 'bar'
const obj = {[property]: value}
const objWithNumberIndex = {[numberProperty]: value}
describe('R.propEq', () => {
it('happy', () => {
const result = propEq(property, value, obj)
result // $ExpectType boolean
})
it('number is property', () => {
const result = propEq(1, value, objWithNumberIndex)
result // $ExpectType boolean
})
it('with optional property', () => {
interface MyType {
optional?: string | number,
}
const myObject: MyType = {}
const valueToFind = '1111'
const optionalValueToFind: string | number | undefined = '1111'
const result = propEq('optional', valueToFind, myObject)
const result2 = propEq('optional', optionalValueToFind, myObject)
result // $ExpectType boolean
result2 // $ExpectType boolean
})
})1 failed Ramda.propEq specs
💥 Reason for the failure: Ramda method pass to equals method if available
💥 Reason for the failure: Ramda method pass to equals method if available
var R = require('../../../../dist/rambda.js');
var eq = require('./shared/eq');
describe('propEq', function() {
var obj1 = {name: 'Abby', age: 7, hair: 'blond'};
var obj2 = {name: 'Fred', age: 12, hair: 'brown'};
it('handles number as property', function() {
var deities = ['Cthulhu', 'Dagon', 'Yog-Sothoth'];
eq(R.propEq(0, 'Cthulhu', deities), true);
eq(R.propEq(1, 'Dagon', deities), true);
eq(R.propEq(2, 'Yog-Sothoth', deities), true);
eq(R.propEq(-1, 'Yog-Sothoth', deities), true);
eq(R.propEq(3, undefined, deities), true);
});
it('has R.equals semantics', function() {
function Just(x) { this.value = x; }
Just.prototype.equals = function(x) {
return x instanceof Just && R.equals(x.value, this.value);
};
eq(R.propEq('value', 0, {value: -0}), false);
eq(R.propEq('value', -0, {value: 0}), false);
eq(R.propEq('value', NaN, {value: NaN}), true);
eq(R.propEq('value', new Just([42]), {value: new Just([42])}), true);
});
});propIs
propIs(type: any, name: string, obj: any): booleanIt returns true if property of obj is from target type.
const obj = {a:1, b: 'foo'}
const property = 'foo'
const result = [
R.propIs(String, property, obj),
R.propIs(Number, property, obj)
]
// => [true, false]Try the above R.propIs example in Rambda REPL
All Typescript definitions
propIs(type: any, name: string, obj: any): boolean;
propIs(type: any, name: string): (obj: any) => boolean;
propIs(type: any): {
(name: string, obj: any): boolean;
(name: string): (obj: any) => boolean;
};R.propIs source
import { curry } from './curry'
import { is } from './is'
function propIsFn(
targetPrototype, property, obj
){
return is(targetPrototype, obj[ property ])
}
export const propIs = curry(propIsFn)Tests
import { propIs } from './propIs'
const obj = { value : 1 }
const property = 'value'
test('when true', () => {
expect(propIs(
Number, property, obj
)).toBeTrue()
})
test('when false', () => {
expect(propIs(
String, property, obj
)).toBeFalse()
expect(propIs(
String, property, {}
)).toBeFalse()
})Typescript test
import {propIs} from 'rambda'
const property = 'a'
const obj = {a: 1}
describe('R.propIs', () => {
it('happy', () => {
const result = propIs(Number, property, obj)
result // $ExpectType boolean
})
it('curried', () => {
const result = propIs(Number, property)(obj)
result // $ExpectType boolean
})
})propOr
propOr<T>(defaultValue: T, property: string, obj: { [key: string]: T}): TIt returns either defaultValue or the value of property in obj.
const obj = {a: 1}
const defaultValue = 'DEFAULT_VALUE'
const property = 'a'
const result = [
R.propOr(defaultValue, property, obj),
R.propOr(defaultValue, 'foo', obj)
]
// => [1, 'DEFAULT_VALUE']Try the above R.propOr example in Rambda REPL
All Typescript definitions
propOr<T>(defaultValue: T, property: string, obj: { [key: string]: T}): T;
propOr<T>(defaultValue: T, property: string): (obj: { [key: string]: T}) => T;
propOr<T>(defaultValue: T): FunctionToolbelt.Curry<(property: string, obj: { [key: string]: T}) => T>;R.propOr source
import { curry } from './curry'
import { defaultTo } from './defaultTo'
function propOrFn(
defaultValue, property, obj
){
if (!obj) return defaultValue
return defaultTo(defaultValue, obj[ property ])
}
export const propOr = curry(propOrFn)Tests
import { propOr } from './propOr'
test('propOr (result)', () => {
const obj = { a : 1 }
expect(propOr(
'default', 'a', obj
)).toEqual(1)
expect(propOr(
'default', 'notExist', obj
)).toEqual('default')
expect(propOr(
'default', 'notExist', null
)).toEqual('default')
})
test('propOr (currying)', () => {
const obj = { a : 1 }
expect(propOr('default')('a', obj)).toEqual(1)
expect(propOr('default', 'a')(obj)).toEqual(1)
expect(propOr('default')('notExist', obj)).toEqual('default')
expect(propOr('default', 'notExist')(obj)).toEqual('default')
})Typescript test
import {propOr} from 'rambda'
const obj = {foo: 'bar'}
const property = 'foo'
const fallback = 'fallback'
describe('R.propOr', () => {
it('happy', () => {
const result = propOr(fallback, property, obj)
result // $ExpectType string
})
it('curry 1', () => {
const result = propOr(fallback)(property, obj)
result // $ExpectType string
})
it('curry 2', () => {
const result = propOr(fallback, property)(obj)
result // $ExpectType string
})
it('curry 3', () => {
const result = propOr(fallback)(property)(obj)
result // $ExpectType string
})
})range
range(startInclusive: number, endExclusive: number): number[]It returns list of numbers between startInclusive to endExclusive numbers.
R.range(0, 5)
// => [0, 1, 2, 3, 4]Try the above R.range example in Rambda REPL
All Typescript definitions
range(startInclusive: number, endExclusive: number): number[];
range(startInclusive: number): (endExclusive: number) => number[];R.range source
export function range(start, end){
if (arguments.length === 1) return _end => range(start, _end)
if (Number.isNaN(Number(start)) || Number.isNaN(Number(end))){
throw new TypeError('Both arguments to range must be numbers')
}
if (end < start) return []
const len = end - start
const willReturn = Array(len)
for (let i = 0; i < len; i++){
willReturn[ i ] = start + i
}
return willReturn
}Tests
import { range } from './range'
test('happy', () => {
expect(range(0, 10)).toEqual([ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 ])
})
test('end range is bigger than start range', () => {
expect(range(7, 3)).toEqual([])
expect(range(5, 5)).toEqual([])
})
test('with bad input', () => {
const throwMessage = 'Both arguments to range must be numbers'
expect(() => range('a', 6)).toThrowWithMessage(Error, throwMessage)
expect(() => range(6, 'z')).toThrowWithMessage(Error, throwMessage)
})
test('curry', () => {
expect(range(0)(10)).toEqual([ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 ])
})Typescript test
import {range} from 'rambda'
describe('R.range', () => {
it('happy', () => {
const result = range(1, 4)
result // $ExpectType number[]
})
it('curried', () => {
const result = range(1)(4)
result // $ExpectType number[]
})
})reduce
reduce<T, TResult>(reducer: (prev: TResult, current: T, i: number) => TResult, initialValue: TResult, list: ReadonlyArray<T>): TResultconst list = [1, 2, 3]
const initialValue = 10
const reducer = (prev, current) => prev * current
const result = R.reduce(reducer, initialValue, list)
// => 60Try the above R.reduce example in Rambda REPL
All Typescript definitions
reduce<T, TResult>(reducer: (prev: TResult, current: T, i: number) => TResult, initialValue: TResult, list: ReadonlyArray<T>): TResult;
reduce<T, TResult>(reducer: (prev: TResult, current: T) => TResult, initialValue: TResult, list: ReadonlyArray<T>): TResult;
reduce<T, TResult>(reducer: (prev: TResult, current: T, i?: number) => TResult): (initialValue: TResult, list: ReadonlyArray<T>) => TResult;
reduce<T, TResult>(reducer: (prev: TResult, current: T, i?: number) => TResult, initialValue: TResult): (list: ReadonlyArray<T>) => TResult;R.reduce source
import { _isArray } from './_internals/_isArray'
import { _keys } from './_internals/_keys'
import { curry } from './curry'
function reduceFn(
reducer, acc, list
){
if (!_isArray(list)){
throw new TypeError('reduce: list must be array or iterable')
}
let index = 0
const len = list.length
while (index < len){
acc = reducer(
acc, list[ index ], index, list
)
index++
}
return acc
}
export const reduce = curry(reduceFn)Tests
import { reduce } from './reduce'
const reducer = (
prev, current, i
) => {
expect(i).toBeNumber()
return prev + current
}
const initialValue = 1
const list = [ 1, 2, 3 ]
test('happy', () => {
expect(reduce(
reducer, initialValue, list
)).toEqual(7)
})
test('with object as iterable', () => {
expect(() =>
reduce(
reducer, initialValue, {
a : 1,
b : 2,
}
)).toThrowWithMessage(TypeError, 'reduce: list must be array or iterable')
})
test('with undefined as iterable', () => {
expect(() => reduce(
reducer, initialValue, undefined
)).toThrowWithMessage(TypeError,
'reduce: list must be array or iterable')
})Typescript test
import {reduce} from 'rambda'
describe('R.reduce', () => {
it('happy', () => {
const result = reduce<number, number>(
(acc, elem) => {
acc // $ExpectType number
elem // $ExpectType number
return acc + elem
},
1,
[1, 2, 3]
)
result // $ExpectType number
})
it('with two types', () => {
const result = reduce<number, string>(
(acc, elem) => {
acc // $ExpectType string
elem // $ExpectType number
return `${acc}${elem}`
},
'foo',
[1, 2, 3]
)
result // $ExpectType string
})
it('with index', () => {
const result = reduce<number, number>(
(acc, elem, i) => {
acc // $ExpectType number
elem // $ExpectType number
i // $ExpectType number
return acc + elem
},
1,
[1, 2, 3]
)
result // $ExpectType number
})
it('fallback', () => {
const result = reduce(
(acc, val) => {
acc // $ExpectType number
return acc + val
},
1,
[1, 2, 3]
)
result // $ExpectType number
})
it('fallback with index', () => {
const result = reduce(
(acc, val, i) => {
acc // $ExpectType number
i // $ExpectType number
return acc + val
},
1,
[1, 2, 3]
)
result // $ExpectType number
})
it('fallback with two types', () => {
const result = reduce(
(acc, val) => {
acc // $ExpectType string
return acc + val
},
'foo',
[1, 2, 3]
)
result // $ExpectType string
})
})2 failed Ramda.reduce specs
💥 Reason for the failure: Rambda library doesn't have R.reduced method | Ramda method pass to reduce method
💥 Reason for the failure: Rambda library doesn't have R.reduced method | Ramda method pass to reduce method
var R = require('../../../../dist/rambda.js');
var eq = require('./shared/eq');
describe('reduce', function() {
var add = function(a, b) {return a + b;};
var mult = function(a, b) {return a * b;};
it('Prefers the use of the iterator of an object over reduce (and handles short-circuits)', function() {
var symIterator = (typeof Symbol !== 'undefined') ? Symbol.iterator : '@@iterator';
function Reducible(arr) {
this.arr = arr;
}
Reducible.prototype.reduce = function(f, init) {
var acc = init;
for (var i = 0; i < this.arr.length; i += 1) {
acc = f(acc, this.arr[i]);
}
return acc;
};
Reducible.prototype[symIterator] = function() {
var a = this.arr;
return {
_pos: 0,
next: function() {
if (this._pos < a.length) {
var v = a[this._pos];
this._pos += 1;
return {
value: v,
done: false
};
} else {
return {
done: true
};
}
}
};
};
var xf = R.take(2);
var apendingT = { };
apendingT['@@transducer/result'] = R.identity;
apendingT['@@transducer/step'] = R.flip(R.append);
var rfn = xf(apendingT);
var list = new Reducible([1, 2, 3, 4, 5, 6]);
eq(R.reduce(rfn, [], list), [1, 2]);
});
it('short circuits with reduced', function() {
var addWithMaxOf10 = function(acc, val) {return acc + val > 10 ? R.reduced(acc) : acc + val;};
eq(R.reduce(addWithMaxOf10, 0, [1, 2, 3, 4]), 10);
eq(R.reduce(addWithMaxOf10, 0, [2, 4, 6, 8]), 6);
});
});reject
reject<T>(predicate: FilterFunctionArray<T>): (x: T[]) => T[]It has the opposite effect of R.filter.
It will return those members of list that return false when applied to predicate function.
const list = [1, 2, 3, 4]
const predicate = x => x > 2
const result = [
R.reject(predicate, list)
]
// => [1, 2]Try the above R.reject example in Rambda REPL
All Typescript definitions
reject<T>(predicate: FilterFunctionArray<T>): (x: T[]) => T[];
reject<T>(predicate: FilterFunctionArray<T>, x: T[]): T[];
reject<T, U>(predicate: FilterFunctionObject<T>): (x: Dictionary<T>) => Dictionary<T>;
reject<T>(predicate: FilterFunctionObject<T>, x: Dictionary<T>): Dictionary<T>;R.reject source
import { filter } from './filter'
export function reject(predicate, list){
if (arguments.length === 1) return _list => reject(predicate, _list)
return filter((x, i) => !predicate(x, i), list)
}Tests
import { reject } from './reject'
const isOdd = n => n % 2 === 1
test('with array', () => {
expect(reject(isOdd, [ 1, 2, 3, 4 ])).toEqual([ 2, 4 ])
})
test('with object', () => {
expect(reject(isOdd, {
a : 1,
b : 2,
c : 3,
d : 4,
})).toEqual({
b : 2,
d : 4,
})
})
test('pass index as second argument', () => {
reject((x, i) => {
expect(typeof x).toBe('number')
expect(typeof i).toBe('number')
},
[ 10, 12, 15 ])
})Typescript test
import {reject} from 'rambda'
describe('R.reject with array', () => {
it('1 curry', () => {
const x = reject<number>(a => {
a // $ExpectType number
return a > 1
})([1, 2, 3])
x // $ExpectType number[]
})
it('1', () => {
const x = reject<number>(
a => {
a // $ExpectType number
return a > 1
},
[1, 2, 3]
)
x // $ExpectType number[]
})
it('2', () => {
const x = reject<number>(
(a, b) => {
a // $ExpectType number
return a > 1
},
[1, 2, 3]
)
x // $ExpectType number[]
})
})
describe('R.reject with objects', () => {
it('curried', () => {
const x = reject<number, number>((a, b, c) => {
b // $ExpectType string
c // $ExpectType Dictionary<number>
return a > 1
})({a: 1, b: 2})
x // $ExpectType Dictionary<number>
})
it('object with three arguments predicate', () => {
const x = reject<number>(
(a, b, c) => {
b // $ExpectType string
c // $ExpectType Dictionary<number>
return a > 1
},
{a: 1, b: 2}
)
x // $ExpectType Dictionary<number>
})
it('object with two arguments predicate', () => {
const x = reject<number>(
(a, b) => {
b // $ExpectType string
return a > 1
},
{a: 1, b: 2}
)
x // $ExpectType Dictionary<number>
})
it('object with one argument predicate', () => {
const x = reject<number>(
a => {
a // $ExpectType number
return a > 1
},
{a: 1, b: 2}
)
x // $ExpectType Dictionary<number>
})
})1 failed Ramda.reject specs
💥 Reason for the failure: Ramda method dispatches to filter method
💥 Reason for the failure: Ramda method dispatches to filter method
var R = require('../../../../dist/rambda.js');
var eq = require('./shared/eq');
describe('reject', function() {
var even = function(x) {return x % 2 === 0;};
it('dispatches to `filter` method', function() {
function Nothing() {}
Nothing.value = new Nothing();
Nothing.prototype.filter = function() {
return this;
};
function Just(x) { this.value = x; }
Just.prototype.filter = function(pred) {
return pred(this.value) ? this : Nothing.value;
};
var m = new Just(42);
eq(R.filter(R.T, m), m);
eq(R.filter(R.F, m), Nothing.value);
eq(R.reject(R.T, m), Nothing.value);
eq(R.reject(R.F, m), m);
});
});repeat
repeat<T>(x: T): (timesToRepeat: number) => T[]It returns a list of x input repeated timesToRepeat input.
R.repeat('foo', 3)
// => ['foo', 'foo', 'foo']Try the above R.repeat example in Rambda REPL
All Typescript definitions
repeat<T>(x: T): (timesToRepeat: number) => T[];
repeat<T>(x: T, timesToRepeat: number): T[];R.repeat source
export function repeat(x, timesToRepeat){
if (arguments.length === 1){
return _timesToRepeat => repeat(x, _timesToRepeat)
}
return Array(timesToRepeat).fill(x)
}Tests
import { repeat } from './repeat'
test('repeat', () => {
expect(repeat('')(3)).toEqual([ '', '', '' ])
expect(repeat('foo', 3)).toEqual([ 'foo', 'foo', 'foo' ])
const obj = {}
const arr = repeat(obj, 3)
expect(arr).toEqual([ {}, {}, {} ])
expect(arr[ 0 ] === arr[ 1 ]).toBeTrue()
})Typescript test
import {repeat} from 'rambda'
describe('R.repeat', () => {
it('happy', () => {
const result = repeat(4, 7)
result // $ExpectType number[]
})
it('curried', () => {
const result = repeat(4)(7)
result // $ExpectType number[]
})
})replace
replace(strOrRegex: RegExp | string, replacer: string, str: string): stringIt replaces strOrRegex found in str with replacer.
const strOrRegex = /o/g
const result = R.replace(strOrRegex, '|0|', 'foo')
// => 'f|0||0|'Try the above R.replace example in Rambda REPL
All Typescript definitions
replace(strOrRegex: RegExp | string, replacer: string, str: string): string;
replace(strOrRegex: RegExp | string, replacer: string): (str: string) => string;
replace(strOrRegex: RegExp | string): (replacer: string) => (str: string) => string;R.replace source
import { curry } from './curry'
function replaceFn(
pattern, replacer, str
){
return str.replace(pattern, replacer)
}
export const replace = curry(replaceFn)Tests
import { replace } from './replace'
test('happy', () => {
expect(replace(
'foo', 'yes', 'foo bar baz'
)).toEqual('yes bar baz')
})
test('1', () => {
expect(replace(/\s/g)('|')('foo bar baz')).toEqual('foo|bar|baz')
})
test('2', () => {
expect(replace(/\s/g)('|', 'foo bar baz')).toEqual('foo|bar|baz')
})
test('3', () => {
expect(replace(/\s/g, '|')('foo bar baz')).toEqual('foo|bar|baz')
})Typescript test
import {replace} from 'rambda'
const str = 'foo bar foo'
const replacer = 'bar'
describe('R.replace', () => {
it('happy', () => {
const result = replace(/foo/g, replacer, str)
result // $ExpectType string
})
it('with string as search pattern', () => {
const result = replace('foo', replacer, str)
result // $ExpectType string
})
})
describe('R.replace - curried', () => {
it('happy', () => {
const result = replace(/foo/g, replacer)(str)
result // $ExpectType string
})
it('with string as search pattern', () => {
const result = replace('foo', replacer)(str)
result // $ExpectType string
})
})reverse
reverse<T>(listOrString: ReadonlyArray<T>): T[]It returns a reversed copy of listOrString input.
const result = [
R.reverse('foo'),
R.reverse([1, 2, 3])
]
// => ['oof', [3, 2, 1]Try the above R.reverse example in Rambda REPL
All Typescript definitions
reverse<T>(listOrString: ReadonlyArray<T>): T[];
reverse(listOrString: string): string;R.reverse source
export function reverse(listOrString){
if (typeof listOrString === 'string'){
return listOrString.split('').reverse()
.join('')
}
const clone = listOrString.slice()
return clone.reverse()
}Tests
import { reverse } from './reverse'
test('happy', () => {
expect(reverse([ 1, 2, 3 ])).toEqual([ 3, 2, 1 ])
})
test('with string', () => {
expect(reverse('baz')).toEqual('zab')
})
test('it doesn\'t mutate', () => {
const arr = [ 1, 2, 3 ]
expect(reverse(arr)).toEqual([ 3, 2, 1 ])
expect(arr).toEqual([ 1, 2, 3 ])
})Typescript test
import {reverse} from 'rambda'
const list = [1, 2, 3, 4, 5]
describe('R.reverse', () => {
it('happy', () => {
const result = reverse(list)
result // $ExpectType number[]
})
})set
set<T, U>(lens: Lens, replacer: U, obj: T): TIt returns a copied Object or Array with modified lens focus set to replacer value.
const input = {x: 1, y: 2}
const xLens = R.lensProp('x')
R.set(xLens, 4, input) //=> {x: 4, y: 2}
R.set(xLens, 8, input) //=> {x: 8, y: 2}Try the above R.set example in Rambda REPL
All Typescript definitions
set<T, U>(lens: Lens, replacer: U, obj: T): T;
set<U>(lens: Lens, replacer: U): <T>(obj: T) => T;
set(lens: Lens): <T, U>(replacer: U, obj: T) => T;R.set source
import { always } from './always'
import { curry } from './curry'
import { over } from './over'
function setFn(
lens, replacer, x
){
return over(
lens, always(replacer), x
)
}
export const set = curry(setFn)slice
slice(from: number, to: number, list: string): stringIt returns listOrString between from and to indexes.
const list = [0, 1, 2, 3, 4, 5]
const str = 'FOO_BAR'
const from = 1
const to = 4
const result = [
R.slice(str, to, list),
R.slice(from, to, list)
]
// => ['OO_', [1, 2, 3]]Try the above R.slice example in Rambda REPL
All Typescript definitions
slice(from: number, to: number, list: string): string;
slice<T>(from: number, to: number, list: T[]): T[];
slice(from: number, to: number): {
(list: string): string;
<T>(list: T[]): T[];
};
slice(from: number): {
(to: number, list: string): string;
<T>(to: number, list: T[]): T[];
};R.slice source
import { curry } from './curry'
function sliceFn(
from, to, list
){
return list.slice(from, to)
}
export const slice = curry(sliceFn)Tests
import { slice } from './slice'
test('slice', () => {
expect(slice(
1, 3, [ 'a', 'b', 'c', 'd' ]
)).toEqual([ 'b', 'c' ])
expect(slice(
1, Infinity, [ 'a', 'b', 'c', 'd' ]
)).toEqual([ 'b', 'c', 'd' ])
expect(slice(
0, -1, [ 'a', 'b', 'c', 'd' ]
)).toEqual([ 'a', 'b', 'c' ])
expect(slice(
-3, -1, [ 'a', 'b', 'c', 'd' ]
)).toEqual([ 'b', 'c' ])
expect(slice(
0, 3, 'ramda'
)).toEqual('ram')
})Typescript test
import {slice} from 'rambda'
const list = [1, 2, 3, 4, 5]
describe('R.slice', () => {
it('happy', () => {
const result = slice(1, 3, list)
result // $ExpectType number[]
})
it('curried', () => {
const result = slice(1, 3)(list)
result // $ExpectType number[]
})
})sort
sort<T>(sortFn: (a: T, b: T) => number, list: ReadonlyArray<T>): T[]It returns copy of list sorted by sortFn function.
const list = [
{a: 2},
{a: 3},
{a: 1}
]
const sortFn = (x, y) => {
return x.a > y.a ? 1 : -1
}
const result = R.sort(sortFn, list)
const expected = [
{a: 1},
{a: 2},
{a: 3}
]
// => `result` is equal to `expected`Try the above R.sort example in Rambda REPL
All Typescript definitions
sort<T>(sortFn: (a: T, b: T) => number, list: ReadonlyArray<T>): T[];
sort<T>(sortFn: (a: T, b: T) => number): (list: ReadonlyArray<T>) => T[];R.sort source
export function sort(sortFn, list){
if (arguments.length === 1) return _list => sort(sortFn, _list)
const clone = list.slice()
return clone.sort(sortFn)
}Tests
import { sort } from './sort'
const fn = (a, b) => a > b ? 1 : -1
test('sort', () => {
expect(sort((a, b) => a - b)([ 2, 3, 1 ])).toEqual([ 1, 2, 3 ])
})
test('it doesn\'t mutate', () => {
const list = [ 'foo', 'bar', 'baz' ]
expect(sort(fn, list)).toEqual([ 'bar', 'baz', 'foo' ])
expect(list[ 0 ]).toBe('foo')
expect(list[ 1 ]).toBe('bar')
expect(list[ 2 ]).toBe('baz')
})Typescript test
import {sort} from 'rambda'
const list = [3, 0, 5, 2, 1]
function sortFn(a: number, b: number): number {
return a > b ? 1 : -1
}
describe('R.sort', () => {
it('happy', () => {
const result = sort(sortFn, list)
result // $ExpectType number[]
})
it('curried', () => {
const result = sort(sortFn)(list)
result // $ExpectType number[]
})
})sortBy
sortBy<T>(sortFn: (a: T) => Ord, list: ReadonlyArray<T>): T[]It returns copy of list sorted by sortFn function.
const list = [
{a: 2},
{a: 3},
{a: 1}
]
const sortFn = x => x.a
const result = R.sortBy(sortFn, list)
const expected = [
{a: 1},
{a: 2},
{a: 3}
]
// => `result` is equal to `expected`Try the above R.sortBy example in Rambda REPL
All Typescript definitions
sortBy<T>(sortFn: (a: T) => Ord, list: ReadonlyArray<T>): T[];
sortBy(sortFn: (a: any) => Ord): <T>(list: ReadonlyArray<T>) => T[];R.sortBy source
export function sortBy(sortFn, list){
if (arguments.length === 1) return _list => sortBy(sortFn, _list)
const clone = list.slice()
return clone.sort((a, b) => {
const aSortResult = sortFn(a)
const bSortResult = sortFn(b)
if (aSortResult === bSortResult) return 0
return aSortResult < bSortResult ? -1 : 1
})
}Tests
import { compose } from './compose'
import { prop } from './prop'
import { sortBy } from './sortBy'
import { toLower } from './toLower'
test('happy', () => {
const input = [ { a : 2 }, { a : 1 }, { a : 1 }, { a : 3 } ]
const expected = [ { a : 1 }, { a : 1 }, { a : 2 }, { a : 3 } ]
const result = sortBy(x => x.a)(input)
expect(result).toEqual(expected)
})
test('with compose', () => {
const alice = {
name : 'ALICE',
age : 101,
}
const bob = {
name : 'Bob',
age : -10,
}
const clara = {
name : 'clara',
age : 314.159,
}
const people = [ clara, bob, alice ]
const sortByNameCaseInsensitive = sortBy(compose(toLower, prop('name')))
expect(sortByNameCaseInsensitive(people)).toEqual([ alice, bob, clara ])
})Typescript test
import {sortBy} from 'rambda'
interface Input {
a: number,
}
describe('R.sortBy', () => {
it('passing type to sort function', () => {
function fn(x: any): number {
return x.a
}
function fn2(x: Input): number {
return x.a
}
const input = [{a: 2}, {a: 1}, {a: 0}]
const result = sortBy(fn, input)
const curriedResult = sortBy(fn2)(input)
result // $ExpectType { a: number; }[]
curriedResult // $ExpectType { a: number; }[]
result[0].a // $ExpectType number
})
it('passing type to sort function and list', () => {
function fn(x: Input): number {
return x.a
}
const input: Input[] = [{a: 2}, {a: 1}, {a: 0}]
const result = sortBy(fn, input)
const curriedResult = sortBy(fn)(input)
result // $ExpectType Input[]
curriedResult // $ExpectType Input[]
result[0].a // $ExpectType number
})
})1 failed Ramda.sortBy specs
💥 Reason for the failure: Ramda method works with array-like objects
💥 Reason for the failure: Ramda method works with array-like objects
var R = require('../../../../dist/rambda.js');
var eq = require('./shared/eq');
var albums = [
{title: 'Art of the Fugue', artist: 'Glenn Gould', genre: 'Baroque'},
{title: 'A Farewell to Kings', artist: 'Rush', genre: 'Rock'},
{title: 'Timeout', artist: 'Dave Brubeck Quartet', genre: 'Jazz'},
{title: 'Fly By Night', artist: 'Rush', genre: 'Rock'},
{title: 'Goldberg Variations', artist: 'Daniel Barenboim', genre: 'Baroque'},
{title: 'New World Symphony', artist: 'Leonard Bernstein', genre: 'Romantic'},
{title: 'Romance with the Unseen', artist: 'Don Byron', genre: 'Jazz'},
{title: 'Somewhere In Time', artist: 'Iron Maiden', genre: 'Metal'},
{title: 'In Times of Desparation', artist: 'Danny Holt', genre: 'Modern'},
{title: 'Evita', artist: 'Various', genre: 'Broadway'},
{title: 'Five Leaves Left', artist: 'Nick Drake', genre: 'Folk'},
{title: 'The Magic Flute', artist: 'John Eliot Gardiner', genre: 'Classical'}
];
describe('sortBy', function() {
it('sorts array-like object', function() {
var args = (function() { return arguments; }('c', 'a', 'b'));
var result = R.sortBy(R.identity, args);
eq(result[0], 'a');
eq(result[1], 'b');
eq(result[2], 'c');
});
});split
split(separator: string | RegExp): (str: string) => string[]Curried version of String.prototype.split
const str = 'foo|bar|baz'
const separator = |'
const result = R.split(separator, str))
// => [ 'foo', 'bar', 'baz' ]Try the above R.split example in Rambda REPL
All Typescript definitions
split(separator: string | RegExp): (str: string) => string[];
split(separator: string | RegExp, str: string): string[];R.split source
export function split(separator, str){
if (arguments.length === 1) return _str => split(separator, _str)
return str.split(separator)
}Tests
import { split } from './split'
const str = 'foo|bar|baz'
const splitChar = '|'
const expected = [ 'foo', 'bar', 'baz' ]
test('happy', () => {
expect(split(splitChar, str)).toEqual(expected)
})
test('curried', () => {
expect(split(splitChar)(str)).toEqual(expected)
})Typescript test
import {split} from 'rambda'
const str = 'foo|bar|baz'
const splitChar = '|'
describe('R.split', () => {
it('happy', () => {
const result = split(splitChar, str)
result // $ExpectType string[]
})
it('curried', () => {
const result = split(splitChar)(str)
result // $ExpectType string[]
})
})splitEvery
splitEvery<T>(sliceLength: number, listOrString: ReadonlyArray<T>): T[][]It splits listOrString into slices of sliceLength.
const result = [
R.splitEvery(2, [1, 2, 3]),
R.splitEvery(3, 'foobar')
]
const expected = [
[[1, 2], [3]],
['foo', 'bar']
]
// => `result` is equal to `expected`Try the above R.splitEvery example in Rambda REPL
All Typescript definitions
splitEvery<T>(sliceLength: number, listOrString: ReadonlyArray<T>): T[][];
splitEvery(sliceLength: number, listOrString: string): string[];
splitEvery(sliceLength: number): {
(listOrString: string): string[];
<T>(listOrString: ReadonlyArray<T>): T[][];
};R.splitEvery source
export function splitEvery(sliceLength, listOrString){
if (arguments.length === 1){
return _listOrString => splitEvery(sliceLength, _listOrString)
}
if (sliceLength < 1){
throw new Error('First argument to splitEvery must be a positive integer')
}
const willReturn = []
let counter = 0
while (counter < listOrString.length){
willReturn.push(listOrString.slice(counter, counter += sliceLength))
}
return willReturn
}Tests
import { splitEvery } from './splitEvery'
test('happy', () => {
expect(splitEvery(3, [ 1, 2, 3, 4, 5, 6, 7 ])).toEqual([
[ 1, 2, 3 ],
[ 4, 5, 6 ],
[ 7 ],
])
expect(splitEvery(3)('foobarbaz')).toEqual([ 'foo', 'bar', 'baz' ])
})
test('with bad input', () => {
expect(() =>
expect(splitEvery(0)('foo')).toEqual([ 'f', 'o', 'o' ])).toThrowWithMessage(Error,
'First argument to splitEvery must be a positive integer')
})Typescript test
import {splitEvery} from 'rambda'
const list = [1, 2, 3, 4, 5, 6, 7]
describe('R.splitEvery', () => {
it('happy', () => {
const result = splitEvery(3, list)
result // $ExpectType number[][]
})
it('curried', () => {
const result = splitEvery(3)(list)
result // $ExpectType number[][]
})
})startsWith
startsWith(target: string, str: string): booleanCurried version of String.prototype.startsWith
const str = 'foo-bar'
const result = [
R.startsWith('foo', str),
R.startsWith('bar', str)
]
// => [true, false]Try the above R.startsWith example in Rambda REPL
All Typescript definitions
startsWith(target: string, str: string): boolean;
startsWith(target: string): (str: string) => boolean;R.startsWith source
export function startsWith(target, str){
if (arguments.length === 1) return _str => startsWith(target, _str)
return str.startsWith(target)
}Tests
import { startsWith } from './startsWith'
test('true', () => {
const result = startsWith('foo', 'foo-bar')
expect(result).toBeTrue()
})
test('false', () => {
const result = startsWith('baz')('foo-bar')
expect(result).toBeFalse()
})Typescript test
import {startsWith} from 'rambda'
const target = 'foo'
const input = 'foo bar'
describe('R.startsWith', () => {
it('happy', () => {
const result = startsWith(target, input)
result // $ExpectType boolean
})
it('curried', () => {
const result = startsWith(target)(input)
result // $ExpectType boolean
})
})4 failed Ramda.startsWith specs
💥 Reason for the failure: Rambda method doesn't support arrays
💥 Reason for the failure: Rambda method doesn't support arrays
var R = require('../../../../dist/rambda.js');
var eq = require('./shared/eq');
describe('startsWith', function() {
it('should return true when an array starts with the provided value', function() {
eq(R.startsWith(['a'], ['a', 'b', 'c']), true);
});
it('should return true when an array starts with the provided values', function() {
eq(R.startsWith(['a', 'b'], ['a', 'b', 'c']), true);
});
it('should return false when an array does not start with the provided value', function() {
eq(R.startsWith(['b'], ['a', 'b', 'c']), false);
});
it('should return false when an array does not start with the provided values', function() {
eq(R.startsWith(['b', 'c'], ['a', 'b', 'c']), false);
});
});subtract
subtract(x: number, y: number): numberCurried version of x - y
const x = 3
const y = 1
R.subtract(x, y)
// => 2Try the above R.subtract example in Rambda REPL
All Typescript definitions
subtract(x: number, y: number): number;
subtract(x: number): (y: number) => number;R.subtract source
export function subtract(a, b){
if (arguments.length === 1) return _b => subtract(a, _b)
return a - b
}Tests
import { subtract } from './subtract'
test('happy', () => {
expect(subtract(2, 1)).toEqual(1)
expect(subtract(2)(1)).toEqual(1)
})sum
sum(list: ReadonlyArray<number>): numberR.sum([1, 2, 3, 4, 5])
// => 15Try the above R.sum example in Rambda REPL
All Typescript definitions
sum(list: ReadonlyArray<number>): number;R.sum source
export function sum(list){
return list.reduce((prev, current) => prev + current, 0)
}Tests
import { sum } from './sum'
test('happy', () => {
expect(sum([ 1, 2, 3, 4, 5 ])).toBe(15)
})symmetricDifference
symmetricDifference<T>(x: ReadonlyArray<T>, y: ReadonlyArray<T>): T[]It returns a merged list of x and y with all equal elements removed.
const x = [ 1, 2, 3, 4 ]
const y = [ 3, 4, 5, 6 ]
const result = symmetricDifference(x, y)
// => [ 1, 2, 5, 6 ]Try the above R.symmetricDifference example in Rambda REPL
All Typescript definitions
symmetricDifference<T>(x: ReadonlyArray<T>, y: ReadonlyArray<T>): T[];
symmetricDifference<T>(x: ReadonlyArray<T>): <T>(y: ReadonlyArray<T>) => T[];R.symmetricDifference source
import { concat } from './concat'
import { filter } from './filter'
import { includes } from './includes'
export function symmetricDifference(x, y){
if (arguments.length === 1){
return _y => symmetricDifference(x, _y)
}
return concat(filter(value => !includes(value, y), x),
filter(value => !includes(value, x), y))
}Tests
import { symmetricDifference } from './symmetricDifference'
test('symmetricDifference', () => {
const list1 = [ 1, 2, 3, 4 ]
const list2 = [ 3, 4, 5, 6 ]
expect(symmetricDifference(list1)(list2)).toEqual([ 1, 2, 5, 6 ])
expect(symmetricDifference([], [])).toEqual([])
})
test('symmetricDifference with objects', () => {
const list1 = [ { id : 1 }, { id : 2 }, { id : 3 }, { id : 4 } ]
const list2 = [ { id : 3 }, { id : 4 }, { id : 5 }, { id : 6 } ]
expect(symmetricDifference(list1)(list2)).toEqual([
{ id : 1 },
{ id : 2 },
{ id : 5 },
{ id : 6 },
])
})Typescript test
import {symmetricDifference} from 'rambda'
describe('R.symmetricDifference', () => {
it('happy', () => {
const list1 = [1, 2, 3, 4]
const list2 = [3, 4, 5, 6]
const result = symmetricDifference(list1, list2)
result // $ExpectType number[]
})
it('curried', () => {
const list1 = [{id: 1}, {id: 2}, {id: 3}, {id: 4}]
const list2 = [{id: 3}, {id: 4}, {id: 5}, {id: 6}]
const result = symmetricDifference(list1)(list2)
result // $ExpectType { id: number; }[]
})
})T
T(): booleanR.T()
// => trueTry the above R.T example in Rambda REPL
All Typescript definitions
T(): boolean;R.T source
export function T(){
return true
}tail
tail<T>(listOrString: ReadonlyArray<T>): T[]It returns all but the first element of listOrString.
const result = [
R.tail([1, 2, 3]),
R.tail('foo')
]
// => [[2, 3], 'oo']Try the above R.tail example in Rambda REPL
All Typescript definitions
tail<T>(listOrString: ReadonlyArray<T>): T[];
tail(listOrString: string): string;R.tail source
import { drop } from './drop'
export function tail(listOrString){
return drop(1, listOrString)
}Tests
import { tail } from './tail'
test('tail', () => {
expect(tail([ 1, 2, 3 ])).toEqual([ 2, 3 ])
expect(tail([ 1, 2 ])).toEqual([ 2 ])
expect(tail([ 1 ])).toEqual([])
expect(tail([])).toEqual([])
expect(tail('abc')).toEqual('bc')
expect(tail('ab')).toEqual('b')
expect(tail('a')).toEqual('')
expect(tail('')).toEqual('')
})Typescript test
import {tail} from 'rambda'
describe('R.tail', () => {
it('with string', () => {
const result = tail('foo')
result // $ExpectType string
})
it('with list', () => {
const result = tail([1, 2, 3])
result // $ExpectType number[]
})
})take
take<T>(howMany: number, listOrString: ReadonlyArray<T>): T[]It returns the first howMany elements of listOrString.
const howMany = 2
const result = [
R.take(howMany, [1, 2, 3]),
R.take(howMany, 'foobar'),
]
// => [[1, 2], 'fo']Try the above R.take example in Rambda REPL
All Typescript definitions
take<T>(howMany: number, listOrString: ReadonlyArray<T>): T[];
take(howMany: number, listOrString: string): string;
take<T>(howMany: number): {
<T>(listOrString: readonly T[]): T[];
(listOrString: string): string;
};R.take source
import baseSlice from './_internals/baseSlice'
export function take(howMany, listOrString){
if (arguments.length === 1)
return _listOrString => take(howMany, _listOrString)
if (howMany < 0) return listOrString.slice()
if (typeof listOrString === 'string') return listOrString.slice(0, howMany)
return baseSlice(
listOrString, 0, howMany
)
}Tests
import { take } from './take'
test('happy', () => {
const arr = [ 'foo', 'bar', 'baz' ]
expect(take(1, arr)).toEqual([ 'foo' ])
expect(arr).toEqual([ 'foo', 'bar', 'baz' ])
expect(take(2)([ 'foo', 'bar', 'baz' ])).toEqual([ 'foo', 'bar' ])
expect(take(3, [ 'foo', 'bar', 'baz' ])).toEqual([ 'foo', 'bar', 'baz' ])
expect(take(4, [ 'foo', 'bar', 'baz' ])).toEqual([ 'foo', 'bar', 'baz' ])
expect(take(3)('rambda')).toEqual('ram')
})
test('with negative index', () => {
expect(take(-1, [ 1, 2, 3 ])).toEqual([ 1, 2, 3 ])
expect(take(-Infinity, [ 1, 2, 3 ])).toEqual([ 1, 2, 3 ])
})
test('with zero index', () => {
expect(take(0, [ 1, 2, 3 ])).toEqual([])
})Typescript test
import {take} from 'rambda'
const list = [1, 2, 3, 4]
const str = 'foobar'
const howMany = 2
describe('R.take - array', () => {
it('happy', () => {
const result = take(howMany, list)
result // $ExpectType number[]
})
it('curried', () => {
const result = take(howMany)(list)
result // $ExpectType number[]
})
})
describe('R.take - string', () => {
it('happy', () => {
const result = take(howMany, str)
result // $ExpectType string
})
it('curried', () => {
const result = take(howMany)(str)
result // $ExpectType string
})
})3 failed Ramda.take specs
💥 Reason for the failure: Rambda library doesn't have 'R.into` method
💥 Reason for the failure: Rambda library doesn't have 'R.into` method
var assert = require('assert');
var sinon = require('sinon');
var R = require('../../../../dist/rambda.js');
var eq = require('./shared/eq');
describe('take', function() {
it('handles zero correctly (#1224)', function() {
eq(R.into([], R.take(0), [1, 2, 3]), []);
});
it('steps correct number of times', function() {
var spy = sinon.spy();
R.into([], R.compose(R.map(spy), R.take(2)), [1, 2, 3]);
sinon.assert.calledTwice(spy);
});
it('transducer called for every member of list if `n` is < 0', function() {
var spy = sinon.spy();
R.into([], R.compose(R.map(spy), R.take(-1)), [1, 2, 3]);
sinon.assert.calledThrice(spy);
});
});takeLast
takeLast<T>(howMany: number, listOrString: ReadonlyArray<T>): T[]It returns the last howMany elements of listOrString.
const howMany = 2
const result = [
R.takeLast(howMany, [1, 2, 3]),
R.takeLast(howMany, 'foobar'),
]
// => [[2, 3], 'ar']Try the above R.takeLast example in Rambda REPL
All Typescript definitions
takeLast<T>(howMany: number, listOrString: ReadonlyArray<T>): T[];
takeLast(howMany: number, listOrString: string): string;
takeLast<T>(howMany: number): {
<T>(listOrString: readonly T[]): T[];
(listOrString: string): string;
};R.takeLast source
import baseSlice from './_internals/baseSlice'
export function takeLast(howMany, listOrString){
if (arguments.length === 1)
return _listOrString => takeLast(howMany, _listOrString)
const len = listOrString.length
if (howMany < 0) return listOrString.slice()
let numValue = howMany > len ? len : howMany
if (typeof listOrString === 'string')
return listOrString.slice(len - numValue)
numValue = len - numValue
return baseSlice(
listOrString, numValue, len
)
}Tests
import { takeLast } from './takeLast'
test('with arrays', () => {
expect(takeLast(1, [ 'foo', 'bar', 'baz' ])).toEqual([ 'baz' ])
expect(takeLast(2)([ 'foo', 'bar', 'baz' ])).toEqual([ 'bar', 'baz' ])
expect(takeLast(3, [ 'foo', 'bar', 'baz' ])).toEqual([ 'foo', 'bar', 'baz' ])
expect(takeLast(4, [ 'foo', 'bar', 'baz' ])).toEqual([ 'foo', 'bar', 'baz' ])
expect(takeLast(10, [ 'foo', 'bar', 'baz' ])).toEqual([ 'foo', 'bar', 'baz' ])
})
test('with strings', () => {
expect(takeLast(3, 'rambda')).toEqual('bda')
expect(takeLast(7, 'rambda')).toEqual('rambda')
})
test('with negative index', () => {
expect(takeLast(-1, [ 1, 2, 3 ])).toEqual([ 1, 2, 3 ])
expect(takeLast(-Infinity, [ 1, 2, 3 ])).toEqual([ 1, 2, 3 ])
})Typescript test
import {takeLast} from 'rambda'
const list = [1, 2, 3, 4]
const str = 'foobar'
const howMany = 2
describe('R.takeLast - array', () => {
it('happy', () => {
const result = takeLast(howMany, list)
result // $ExpectType number[]
})
it('curried', () => {
const result = takeLast(howMany)(list)
result // $ExpectType number[]
})
})
describe('R.takeLast - string', () => {
it('happy', () => {
const result = takeLast(howMany, str)
result // $ExpectType string
})
it('curried', () => {
const result = takeLast(howMany)(str)
result // $ExpectType string
})
})takeWhile
takeWhile<T>(predicate: (x: T) => boolean, list: readonly T[]): T[]const list = [1, 2, 3, 4]
const predicate = (x) => x < 3
const result = takeWhile(predicate, list)
// => [1, 2, 3]Try the above R.takeWhile example in Rambda REPL
All Typescript definitions
takeWhile<T>(predicate: (x: T) => boolean, list: readonly T[]): T[];
takeWhile<T>(predicate: (x: T) => boolean): (list: readonly T[]) => T[];R.takeWhile source
export function takeWhile(predicate, list){
const toReturn = []
let stopFlag = false
let counter = -1
while (stopFlag === false && counter++ < list.length){
if (!predicate(list[ counter ])){
stopFlag = true
} else {
toReturn.push(list[ counter ])
}
}
return toReturn
}Tests
import { takeWhile } from './takeWhile'
const list = [ 1, 2, 3, 4, 5, 6 ]
test('happy', () => {
const result = takeWhile(x => x < 4, list)
expect(result).toEqual([ 1, 2, 3 ])
})
test('predicate never returns true', () => {
const result = takeWhile(x => x < 10, list)
expect(result).toEqual(list)
})
test('predicate initially returns false', () => {
const result = takeWhile(x => x > 2, list)
expect(result).toEqual([])
})Typescript test
import {takeWhile} from 'rambda'
const list = [1, 2, 3, 4]
const predicate = (x: number) => x > 3
describe('R.takeWhile', () => {
it('happy', () => {
const result = takeWhile(predicate, list)
result // $ExpectType number[]
})
it('curried', () => {
const result = takeWhile(predicate)(list)
result // $ExpectType number[]
})
})2 failed Ramda.takeWhile specs
💥 Reason for the failure: Ramda method works with strings not only arrays
tap
tap<T>(fn: (a: T) => any, x: T): TIt applies function fn to input x and returns x.
One use case is debuging in the middle of R.compose.
const list = [1, 2, 3]
R.compose(
R.map(x => x * 2)
R.tap(console.log),
R.filter(x => x > 1)
)(list)
// => `2` and `3` will be loggedTry the above R.tap example in Rambda REPL
All Typescript definitions
tap<T>(fn: (a: T) => any, x: T): T;
tap<T>(fn: (a: T) => any): (x: T) => T;R.tap source
export function tap(fn, x){
if (arguments.length === 1) return _x => tap(fn, _x)
fn(x)
return x
}Tests
import { tap } from './tap'
test('tap', () => {
let a = 1
const sayX = x => a = x
expect(tap(sayX, 100)).toEqual(100)
expect(tap(sayX)(100)).toEqual(100)
expect(a).toEqual(100)
})Typescript test
import {tap, pipe} from 'rambda'
describe('R.tap', () => {
it('happy', () => {
pipe(
tap(x => {
x // $ExpectType number[]
}),
(x: number[]) => x.length
)([1, 2])
})
})2 failed Ramda.tap specs
💥 Reason for the failure: Ramda method can act as a transducer
💥 Reason for the failure: Ramda method can act as a transducer
var R = require('../../../../dist/rambda.js');
var eq = require('./shared/eq');
var listXf = require('./helpers/listXf');
var _curry2 = require('rambda/internal/_curry2');
describe('tap', function() {
var pushToList = _curry2(function(lst, x) { lst.push(x); });
it('can act as a transducer', function() {
var sideEffect = [];
var numbers = [1,2,3,4,5];
var xf = R.compose(R.map(R.identity), R.tap(pushToList(sideEffect)));
eq(R.into([], xf, numbers), numbers);
eq(sideEffect, numbers);
});
it('dispatches to transformer objects', function() {
var sideEffect = [];
var pushToSideEffect = pushToList(sideEffect);
eq(R.tap(pushToSideEffect, listXf), {
f: pushToSideEffect,
xf: listXf
});
});
});test
test(regExpression: RegExp): (str: string) => booleanIt determines whether str matches regExpression.
R.test(/^f/, 'foo')
// => trueTry the above R.test example in Rambda REPL
All Typescript definitions
test(regExpression: RegExp): (str: string) => boolean;
test(regExpression: RegExp, str: string): boolean;R.test source
export function test(pattern, str){
if (arguments.length === 1) return _str => test(pattern, _str)
if (typeof pattern === 'string'){
throw new TypeError(`‘test’ requires a value of type RegExp as its first argument; received "${ pattern }"`)
}
return str.search(pattern) !== -1
}Tests
import { test as testMethod } from './test'
test('happy', () => {
expect(testMethod(/^x/, 'xyz')).toBeTrue()
expect(testMethod(/^y/)('xyz')).toBeFalse()
})
test('throws if first argument is not regex', () => {
expect(() => testMethod('foo', 'bar')).toThrowWithMessage(TypeError,
'‘test’ requires a value of type RegExp as its first argument; received "foo"')
})Typescript test
import {test} from 'rambda'
const input = 'foo '
const regex = /foo/
describe('R.test', () => {
it('happy', () => {
const result = test(regex, input)
result // $ExpectType boolean
})
it('curried', () => {
const result = test(regex)(input)
result // $ExpectType boolean
})
})times
times<T>(fn: (i: number) => T, howMany: number): T[]It returns the result of applying function fn over members of range array.
The range array includes numbers between 0 and howMany(exclusive).
const fn = x => x * 2
const howMany = 5
R.times(fn, howMany)
//=> [0, 2, 4, 6, 8]Try the above R.times example in Rambda REPL
All Typescript definitions
times<T>(fn: (i: number) => T, howMany: number): T[];
times<T>(fn: (i: number) => T): (howMany: number) => T[];R.times source
import { map } from './map'
import { range } from './range'
export function times(fn, howMany){
if (arguments.length === 1) return _howMany => times(fn, _howMany)
if (!Number.isInteger(howMany) || howMany < 0){
throw new RangeError('n must be an integer')
}
return map(fn, range(0, howMany))
}Tests
import assert from 'assert'
import { identity } from './identity'
import { times } from './times'
test('happy', () => {
const result = times(identity, 5)
expect(result).toEqual([ 0, 1, 2, 3, 4 ])
})
test('with bad input', () => {
assert.throws(() => {
times(3)('cheers!')
}, RangeError)
assert.throws(() => {
times(identity, -1)
}, RangeError)
})
test('curry', () => {
const result = times(identity)(5)
expect(result).toEqual([ 0, 1, 2, 3, 4 ])
})Typescript test
import {times, identity} from 'rambda'
describe('R.times', () => {
it('happy', () => {
const result = times(identity, 5)
result // $ExpectType number[]
})
})toLower
toLower(str: string): stringR.toLower('FOO')
// => 'foo'Try the above R.toLower example in Rambda REPL
All Typescript definitions
toLower(str: string): string;R.toLower source
export function toLower(str){
return str.toLowerCase()
}Tests
import { toLower } from './toLower'
test('toLower', () => {
expect(toLower('FOO|BAR|BAZ')).toEqual('foo|bar|baz')
})toPairs
toPairs<S>(obj: { [k: string]: S } | { [k: number]: S }): [string, S][]It transforms an object to a list.
const list = {
a : 1,
b : 2,
c : [ 3, 4 ],
}
const expected = [ [ 'a', 1 ], [ 'b', 2 ], [ 'c', [ 3, 4 ] ] ]
const result = R.toPairs(list)
// => `result` is equal to `expected`Try the above R.toPairs example in Rambda REPL
All Typescript definitions
toPairs<S>(obj: { [k: string]: S } | { [k: number]: S }): [string, S][];R.toPairs source
export function toPairs(obj){
return Object.entries(obj)
}Tests
import { toPairs } from './toPairs'
const obj = {
a : 1,
b : 2,
c : [ 3, 4 ],
}
const expected = [
[ 'a', 1 ],
[ 'b', 2 ],
[ 'c', [ 3, 4 ] ],
]
test('happy', () => {
expect(toPairs(obj)).toEqual(expected)
})Typescript test
import {toPairs} from 'rambda'
const obj = {
a: 1,
b: 2,
c: [3, 4],
}
describe('R.toPairs', () => {
it('happy', () => {
const result = toPairs(obj)
result // $ExpectType [string, number | number[]][]
})
})toString
toString<T>(x: T): stringR.toString([1, 2])
// => '1,2'Try the above R.toString example in Rambda REPL
All Typescript definitions
toString<T>(x: T): string;R.toString source
export function toString(x){
return x.toString()
}Tests
import { toString } from './toString'
test('happy', () => {
expect(toString([ 1, 2, 3 ])).toEqual('1,2,3')
})toUpper
toUpper(str: string): stringR.toUpper('foo')
// => 'FOO'Try the above R.toUpper example in Rambda REPL
All Typescript definitions
toUpper(str: string): string;R.toUpper source
export function toUpper(str){
return str.toUpperCase()
}Tests
import { toUpper } from './toUpper'
test('toUpper', () => {
expect(toUpper('foo|bar|baz')).toEqual('FOO|BAR|BAZ')
})transpose
transpose<T>(list: T[][]): T[][]const list = [[10, 11], [20], [], [30, 31, 32]]
const expected = [[10, 20, 30], [11, 31], [32]]
const result = R.transpose(list)
// => `result` is equal to `expected`Try the above R.transpose example in Rambda REPL
All Typescript definitions
transpose<T>(list: T[][]): T[][];R.transpose source
import { _isArray } from './_internals/_isArray'
export function transpose(array){
return array.reduce((acc, el) => {
el.forEach((nestedEl, i) =>
_isArray(acc[ i ]) ? acc[ i ].push(nestedEl) : acc.push([ nestedEl ]))
return acc
}, [])
}Tests
import { transpose } from './transpose'
test('happy', () => {
const input = [
[ 'a', 1 ],
[ 'b', 2 ],
[ 'c', 3 ],
]
expect(transpose(input)).toEqual([
[ 'a', 'b', 'c' ],
[ 1, 2, 3 ],
])
})
test('when rows are shorter', () => {
const actual = transpose([ [ 10, 11 ], [ 20 ], [], [ 30, 31, 32 ] ])
const expected = [ [ 10, 20, 30 ], [ 11, 31 ], [ 32 ] ]
expect(actual).toEqual(expected)
})
test('with empty array', () => {
expect(transpose([])).toEqual([])
})
test('array with falsy values', () => {
const actual = transpose([
[ true, false, undefined, null ],
[ null, undefined, false, true ],
])
const expected = [
[ true, null ],
[ false, undefined ],
[ undefined, false ],
[ null, true ],
]
expect(actual).toEqual(expected)
})Typescript test
import {transpose} from 'rambda'
const input = [
['a', 1],
['b', 2],
['c', 3],
]
describe('R.transpose', () => {
it('happy', () => {
const result = transpose(input)
result // $ExpectType (string | number)[][]
})
})trim
trim(str: string): stringR.trim(' foo ')
// => 'foo'Try the above R.trim example in Rambda REPL
All Typescript definitions
trim(str: string): string;R.trim source
export function trim(str){
return str.trim()
}Tests
import { trim } from './trim'
test('trim', () => {
expect(trim(' foo ')).toEqual('foo')
})1 failed Ramda.trim specs
💥 Reason for the failure: Ramda method trims all ES5 whitespace
💥 Reason for the failure: Ramda method trims all ES5 whitespace
var R = require('../../../../dist/rambda.js');
var eq = require('./shared/eq');
describe('trim', function() {
var test = '\x09\x0A\x0B\x0C\x0D\x20\xA0\u1680\u180E\u2000\u2001\u2002\u2003\u2004\u2005\u2006\u2007\u2008\u2009\u200A\u202F\u205F\u3000\u2028\u2029\uFEFFHello, World!\x09\x0A\x0B\x0C\x0D\x20\xA0\u1680\u180E\u2000\u2001\u2002\u2003\u2004\u2005\u2006\u2007\u2008\u2009\u200A\u202F\u205F\u3000\u2028\u2029\uFEFF';
it('trims all ES5 whitespace', function() {
eq(R.trim(test), 'Hello, World!');
eq(R.trim(test).length, 13);
});
if (typeof String.prototype.trim !== 'function') {
it('falls back to a shim if String.prototype.trim is not present', function() {
eq(R.trim(' xyz '), 'xyz');
eq(R.trim(test), 'Hello, World!');
eq(R.trim(test).length, 13);
eq(R.trim('\u200b'), '\u200b');
eq(R.trim('\u200b').length, 1);
});
}
});tryCatch
tryCatch<T, U>(
fn: (input: T) => U,
fallback: U
): (input: T) => UIt returns function that runs fn in try/catch block. If there was an error, then fallback is used to return the result. Note that fn can be value or asynchronous/synchronous function(unlike Ramda where fallback can only be a synchronous function).
Please check the tests of R.tryCatch to fully understand how this method works.
const fn = x => x.foo
const result = [
R.tryCatch(fn, false)(null),
R.tryCatch(fn, false)({foo: 'bar'})
]
// => [false, 'bar']Try the above R.tryCatch example in Rambda REPL
All Typescript definitions
tryCatch<T, U>(
fn: (input: T) => U,
fallback: U
): (input: T) => U;
tryCatch<T, U>(
fn: (input: T) => U,
fallback: (input: T) => U
): (input: T) => U;
tryCatch<T>(
fn: (input: any) => Promise<any>,
fallback: T
): (input: any) => Promise<T>;
tryCatch<T>(
fn: (input: any) => Promise<any>,
fallback: (input: any) => Promise<any>,
): (input: any) => Promise<T>;R.tryCatch source
import { isFunction } from './isFunction'
import { isPromise } from './isPromise'
export function tryCatch(fn, fallback){
if (!isFunction(fn)){
throw new Error(`R.tryCatch | fn '${ fn }'`)
}
const passFallback = isFunction(fallback)
if (!isPromise(fn)){
return (...inputs) => {
try {
return fn(...inputs)
} catch (e){
return passFallback ? fallback(e, ...inputs) : fallback
}
}
}
return (...inputs) =>
new Promise(resolve => {
fn(...inputs)
.then(resolve)
.catch(() => {
if (!passFallback){
return resolve(fallback)
}
if (!isPromise(fallback)){
return resolve(fallback(...inputs))
}
fallback(...inputs).then(resolve)
})
})
}Tests
import { delay } from './delay'
import { prop } from './prop'
import { tryCatch } from './tryCatch'
test('throws when fn is not function', () => {
const fn = 'foo'
expect(() => tryCatch(fn, false)(null)).toThrowWithMessage(Error,
'R.tryCatch | fn \'foo\'')
})
test('when fallback is used', () => {
const fn = x => x.x
expect(tryCatch(fn, false)(null)).toBeFalse()
})
test('with json parse', () => {
const good = () => JSON.parse(JSON.stringify({ a : 1 }))
const bad = () => JSON.parse('a{a')
expect(tryCatch(good, 1)(null)).toEqual({ a : 1 })
expect(tryCatch(bad, 1)(null)).toBe(1)
})
test('when fallback is function', () => {
const fn = x => x.x
expect(tryCatch(fn, () => 1)(null)).toBe(1)
})
test('when fn is used', () => {
const fn = prop('x')
expect(tryCatch(fn, false)({})).toBe(undefined)
expect(tryCatch(fn, false)({ x : 1 })).toBe(1)
})
test('fallback receives error object and all initial inputs', () => {
function thrower(
a, b, c
){
void c
throw new Error('throwerError')
}
function catchFn(
e, a, b, c
){
return [ e.message, a, b, c ].join('|')
}
const willThrow = tryCatch(thrower, catchFn)
const result = willThrow(
'A', 'B', 'C'
)
expect(result).toBe('throwerError|A|B|C')
})
test('fallback receives error object', () => {
function throwFn(){
throw new Error(10)
}
function eCatcher(
e, a, b
){
return e.message
}
const willThrow = tryCatch(throwFn, eCatcher)
expect(willThrow([])).toBe('10')
expect(willThrow([ {}, {}, {} ])).toBe('10')
})
test('when async + fallback', async () => {
let called = false
const fn = async input => {
await delay(input)
called = true
return JSON.parse('{a:')
}
expect(await tryCatch(fn, 'fallback')(100)).toBe('fallback')
expect(called).toBeTrue()
})
test('when async + fallback is function', async () => {
let called = false
const fn = async input => {
await delay(input)
called = true
return JSON.parse('{a:')
}
expect(await tryCatch(fn, x => x + 1)(100)).toBe(101)
expect(called).toBeTrue()
})
test('when async + fallback is async', async () => {
let called = false
const fn = async input => {
await delay(input)
called = true
return JSON.parse('{a:')
}
const fallback = async input => {
await delay(10)
return input + 1
}
expect(await tryCatch(fn, fallback)(100)).toBe(101)
expect(called).toBeTrue()
})
test('when async + fn', async () => {
let called = false
const fn = async input => {
await delay(input)
called = true
return input + 1
}
expect(await tryCatch(fn, 'fallback')(100)).toBe(101)
expect(called).toBeTrue()
})Typescript test
import {tryCatch, delay} from 'rambda'
describe('R.tryCatch', () => {
it('synchronous', () => {
const fn = (x: any) => x.x === 1
const result = tryCatch(fn, false)(null)
result // $ExpectType boolean
})
it('synchronous + fallback is function', () => {
const fn = (x: any) => typeof x.x
const fallback = (x: any) => typeof x
const result = tryCatch<any, string>(fn, fallback)(null)
result // $ExpectType string
})
it('asynchronous', async() => {
const fn = async(input: any) => {
return typeof JSON.parse('{a:')
}
const result = await tryCatch<string>(fn, 'fallback')(100)
result // $ExpectType string
})
it('asynchronous + fallback is asynchronous', async() => {
const fn = async(input: any) => {
await delay(100)
return JSON.parse(`{a:${input}`)
}
const fallback = async(input: any) => {
await delay(100)
return 'foo'
}
const result = await tryCatch<string>(fn, fallback)(100)
result // $ExpectType string
})
})1 failed Ramda.tryCatch specs
💥 Reason for the failure: Ramda method returns a function with the same arity
type
type(x: any): "Object" | "Number" | "Boolean" | "String" | "Null" | "Array" | "Function" | "Undefined" | "Async" | "Promise" | "RegExp" | "NaN"It accepts any input and it returns its type.
R.type(() => {}) // => 'Function'
R.type(async () => {}) // => 'Async'
R.type([]) // => 'Array'
R.type({}) // => 'Object'
R.type('foo') // => 'String'
R.type(1) // => 'Number'
R.type(true) // => 'Boolean'
R.type(null) // => 'Null'
R.type(/[A-z]/) // => 'RegExp'
R.type('foo'*1) // => 'NaN'
const delay = ms => new Promise(resolve => {
setTimeout(function () {
resolve()
}, ms)
})
R.type(delay) // => 'Promise'Try the above R.type example in Rambda REPL
All Typescript definitions
type(x: any): "Object" | "Number" | "Boolean" | "String" | "Null" | "Array" | "Function" | "Undefined" | "Async" | "Promise" | "RegExp" | "NaN";R.type source
import { _isArray } from './_internals/_isArray'
export function type(input){
const typeOf = typeof input
if (input === null){
return 'Null'
} else if (input === undefined){
return 'Undefined'
} else if (typeOf === 'boolean'){
return 'Boolean'
} else if (typeOf === 'number'){
return Number.isNaN(input) ? 'NaN' : 'Number'
} else if (typeOf === 'string'){
return 'String'
} else if (_isArray(input)){
return 'Array'
} else if (input instanceof RegExp){
return 'RegExp'
}
const asStr = input && input.toString ? input.toString() : ''
if ([ 'true', 'false' ].includes(asStr)) return 'Boolean'
if (!Number.isNaN(Number(asStr))) return 'Number'
if (asStr.startsWith('async')) return 'Async'
if (asStr === '[object Promise]') return 'Promise'
if (typeOf === 'function') return 'Function'
if (input instanceof String) return 'String'
return 'Object'
}Tests
import { type as ramdaType } from 'ramda'
import { type } from './type'
test('with simple promise', () => {
expect(type(Promise.resolve(1))).toBe('Promise')
})
test('with new Boolean', () => {
expect(type(new Boolean(true))).toBe('Boolean')
})
test('with new String', () => {
expect(type(new String('I am a String object'))).toEqual('String')
})
test('with new Number', () => {
expect(type(new Number(1))).toBe('Number')
})
test('with new promise', () => {
const delay = ms =>
new Promise(resolve => {
setTimeout(() => {
resolve(ms + 110)
}, ms)
})
expect(type(delay(10))).toEqual('Promise')
})
test('async function', () => {
expect(type(async () => {})).toEqual('Async')
})
test('async arrow', () => {
const asyncArrow = async () => {}
expect(type(asyncArrow)).toBe('Async')
})
test('function', () => {
const fn1 = () => {}
const fn2 = function (){}
function fn3(){}
;[ () => {}, fn1, fn2, fn3 ].map(val => {
expect(type(val)).toEqual('Function')
})
})
test('object', () => {
expect(type({})).toEqual('Object')
})
test('number', () => {
expect(type(1)).toEqual('Number')
})
test('boolean', () => {
expect(type(false)).toEqual('Boolean')
})
test('string', () => {
expect(type('foo')).toEqual('String')
})
test('null', () => {
expect(type(null)).toEqual('Null')
})
test('array', () => {
expect(type([])).toEqual('Array')
expect(type([ 1, 2, 3 ])).toEqual('Array')
})
test('regex', () => {
expect(type(/\s/g)).toEqual('RegExp')
})
test('undefined', () => {
expect(type(undefined)).toEqual('Undefined')
})
test('not a number', () => {
expect(type(Number('s'))).toBe('NaN')
})
test('function inside object 1', () => {
const obj = {
f(){
return 4
},
}
expect(type(obj.f)).toBe('Function')
expect(ramdaType(obj.f)).toBe('Function')
})
test('function inside object 2', () => {
const name = 'f'
const obj = {
[ name ](){
return 4
},
}
expect(type(obj.f)).toBe('Function')
expect(ramdaType(obj.f)).toBe('Function')
})Typescript test
import {type} from 'rambda'
describe('R.type', () => {
it('happy', () => {
const result = type(4)
result // $ExpectType RambdaTypes
})
})1 failed Ramda.type specs
💥 Reason for the failure: Ramda method returns 'Number' type to NaN input, while Rambda method returns 'NaN'
💥 Reason for the failure: Ramda method returns 'Number' type to NaN input, while Rambda method returns 'NaN'
var R = require('../../../../dist/rambda.js');
var eq = require('./shared/eq');
describe('type', function() {
// it('"Arguments" if given an arguments object', function() {
// var args = (function() { return arguments; }());
// eq(R.type(args), 'Arguments');
// });
it('"Number" if given the NaN value', function() {
eq(R.type(NaN), 'Number');
});
});union
union<T>(x: Array<T>, y: Array<T>): Array<T>It takes two lists and return a new list containing a merger of both list with removed duplicates.
R.equals is used to compare for duplication, which means that it can be safely used with array of objects.
const result = R.union([1,2,3], [3,4,5]);
//=> [1, 2, 3, 4, 5]Try the above R.union example in Rambda REPL
All Typescript definitions
union<T>(x: Array<T>, y: Array<T>): Array<T>;
union<T>(x: Array<T>): (y: Array<T>) => Array<T>;R.union source
import { includes } from './includes'
export function union(x, y){
if (arguments.length === 1) return _y => union(x, _y)
const toReturn = x.slice()
y.forEach(yInstance => {
if (!includes(yInstance, x)) toReturn.push(yInstance)
})
return toReturn
}Tests
import { union } from './union'
test('happy', () => {
expect(union([ 1, 2 ], [ 2, 3 ])).toEqual([ 1, 2, 3 ])
})
test('with list of objects', () => {
const list1 = [ { a : 1 }, { a : 2 } ]
const list2 = [ { a : 2 }, { a : 3 } ]
const result = union(list1)(list2)
})Typescript test
import {union} from 'rambda'
describe('R.union', () => {
it('happy', () => {
const result = union([1, 2], [2, 3])
result // $ExpectType number[]
})
it('with array of objects - case 1', () => {
const list1 = [{a: 1}, {a: 2}]
const list2 = [{a: 2}, {a: 3}]
const result = union(list1, list2)
result // $ExpectType { a: number; }[]
})
it('with array of objects - case 2', () => {
const list1 = [{a: 1, b: 1}, {a: 2}]
const list2 = [{a: 2}, {a: 3, b: 3}]
const result = union(list1, list2)
result[0].a // $ExpectType number
result[0].b // $ExpectType number | undefined
})
})
describe('R.union - curried', () => {
it('happy', () => {
const result = union([1, 2])([2, 3])
result // $ExpectType number[]
})
it('with array of objects - case 1', () => {
const list1 = [{a: 1}, {a: 2}]
const list2 = [{a: 2}, {a: 3}]
const result = union(list1)(list2)
result // $ExpectType { a: number; }[]
})
it('with array of objects - case 2', () => {
const list1 = [{a: 1, b: 1}, {a: 2}]
const list2 = [{a: 2}, {a: 3, b: 3}]
const result = union(list1)(list2)
result[0].a // $ExpectType number
result[0].b // $ExpectType number | undefined
})
})1 failed Ramda.union specs
💥 Reason for the failure: Ramda library supports fantasy-land
uniq
uniq<T>(list: ReadonlyArray<T>): T[]It returns a new array containing only one copy of each element of list.
const list = [1, 1, {a: 1}, {a: 2}, {a:1}]
R.uniq(list)
// => [1, {a: 1}, {a: 2}]Try the above R.uniq example in Rambda REPL
All Typescript definitions
uniq<T>(list: ReadonlyArray<T>): T[];R.uniq source
import { includes } from './includes'
export function uniq(list){
let index = -1
const willReturn = []
while (++index < list.length){
const value = list[ index ]
if (!includes(value, willReturn)){
willReturn.push(value)
}
}
return willReturn
}Tests
import { uniq } from './uniq'
test('uniq', () => {
expect(uniq([ 1, 2, 3, 3, 3, 1, 2, 0 ])).toEqual([ 1, 2, 3, 0 ])
expect(uniq([ 1, 1, 2, 1 ])).toEqual([ 1, 2 ])
expect([ 1, '1' ]).toEqual([ 1, '1' ])
expect(uniq([ [ 42 ], [ 42 ] ])).toEqual([ [ 42 ] ])
})Typescript test
import {uniq} from 'rambda'
describe('R.uniq', () => {
it('happy', () => {
const result = uniq([1, 2, 3, 3, 3, 1, 2, 0])
result // $ExpectType number[]
})
})2 failed Ramda.uniq specs
💥 Reason for the failure: Ramda method pass to uniq method | Ramda method uses reference equality for functions
💥 Reason for the failure: Ramda method pass to uniq method | Ramda method uses reference equality for functions
var R = require('../../../../dist/rambda.js');
var eq = require('./shared/eq');
describe('uniq', function() {
it('has R.equals semantics', function() {
function Just(x) { this.value = x; }
Just.prototype.equals = function(x) {
return x instanceof Just && R.equals(x.value, this.value);
};
eq(R.uniq([-0, -0]).length, 1);
eq(R.uniq([0, -0]).length, 2);
eq(R.uniq([NaN, NaN]).length, 1);
eq(R.uniq([[1], [1]]).length, 1);
eq(R.uniq([new Just([42]), new Just([42])]).length, 1);
it('handles null and undefined elements', function() {
eq(R.uniq([void 0, null, void 0, null]), [void 0, null]);
it('uses reference equality for functions', function() {
eq(R.uniq([R.add, R.identity, R.add, R.identity, R.add, R.identity]).length, 2);
});uniqWith
uniqWith<T, U>(uniqFn: (x: T, y: T) => boolean, list: ReadonlyArray<T>): T[]It returns a new array containing only one copy of each element in list according to boolean returning function uniqFn.
const list = [
{id: 0, title:'foo'},
{id: 1, title:'bar'},
{id: 2, title:'baz'},
{id: 3, title:'foo'},
{id: 4, title:'bar'},
]
const expected = [
{id: 0, title:'foo'},
{id: 1, title:'bar'},
{id: 2, title:'baz'},
]
const uniqFn = (x,y) => x.title === y.title
const result = R.uniqWith(uniqFn, list)
// => `result` is equal to `expected`Try the above R.uniqWith example in Rambda REPL
All Typescript definitions
uniqWith<T, U>(uniqFn: (x: T, y: T) => boolean, list: ReadonlyArray<T>): T[];
uniqWith<T, U>(uniqFn: (x: T, y: T) => boolean): (list: ReadonlyArray<T>) => T[];R.uniqWith source
import { any } from './any'
export function uniqWith(fn, list){
if (arguments.length === 1) return _list => uniqWith(fn, _list)
let index = -1
const len = list.length
const willReturn = []
while (++index < len){
const value = list[ index ]
const flag = any(willReturnInstance => fn(value, willReturnInstance),
willReturn)
if (!flag){
willReturn.push(value)
}
}
return willReturn
}Tests
import { uniqWith } from './uniqWith'
test('happy', () => {
const input = [
{
id : 0,
title : 'foo',
},
{
id : 1,
title : 'bar',
},
{
id : 2,
title : 'baz',
},
{
id : 3,
title : 'foo',
},
{
id : 4,
title : 'bar',
},
]
const expectedResult = [
{
id : 0,
title : 'foo',
},
{
id : 1,
title : 'bar',
},
{
id : 2,
title : 'baz',
},
]
const fn = (x, y) => x.title === y.title
const result = uniqWith(fn, input)
const curriedResult = uniqWith(fn)(input)
expect(result).toEqual(expectedResult)
expect(curriedResult).toEqual(expectedResult)
})
test('uniqWith', () => {
const input = [
{
id : 0,
title : 'foo',
},
{
id : 1,
title : 'bar',
},
{
id : 2,
title : 'baz',
},
{
id : 3,
title : 'foo',
},
{
id : 4,
title : 'bar',
},
]
const expectedResult = [
{
id : 0,
title : 'foo',
},
{
id : 1,
title : 'bar',
},
{
id : 2,
title : 'baz',
},
]
const fn = (x, y) => x.title === y.title
const result = uniqWith(fn, input)
//const result = uniqWith(Ramda.eqBy(Ramda.prop('title')), input)
expect(result).toEqual(expectedResult)
})Typescript test
import {uniqWith} from 'rambda'
describe('R.uniqWith', () => {
it('happy', () => {
const input = [
{
id: 0,
title: 'foo',
},
{
id: 1,
title: 'bar',
},
{
id: 2,
title: 'baz',
},
{
id: 3,
title: 'foo',
},
{
id: 4,
title: 'bar',
},
]
const fn = (x: any, y: any) => x.title === y.title
const result = uniqWith(fn, input)
result // $ExpectType { id: number; title: string; }[]
})
})unless
unless<T, U>(predicate: (x: T) => boolean, whenFalseFn: (x: T) => U, obj: T): UThe method returns function that will be called with argument input.
If predicate(input) returns false, then the end result will be the outcome of whenFalse(input).
In the other case, the final output will be the input itself.
const fn = R.unless(
x => x > 2,
x => x + 10
)
const result = [
fn(1),
fn(5)
]
// => [11, 5]Try the above R.unless example in Rambda REPL
All Typescript definitions
unless<T, U>(predicate: (x: T) => boolean, whenFalseFn: (x: T) => U, obj: T): U;
unless<T, U>(predicate: (x: T) => boolean, whenFalseFn: (x: T) => U): (obj: T) => U;R.unless source
export function unless(predicate, whenFalse){
if (arguments.length === 1){
return _whenFalse => unless(predicate, _whenFalse)
}
return input => {
if (predicate(input)) return input
return whenFalse(input)
}
}Tests
import { inc } from './inc'
import { isNil } from './isNil'
import { unless } from './unless'
const safeInc = unless(isNil, inc)
test('happy', () => {
expect(safeInc(null)).toBeNull()
expect(safeInc(1)).toBe(2)
})
test('curried', () => {
const safeIncCurried = unless(isNil)(inc)
expect(safeIncCurried(null)).toBeNull()
expect(safeIncCurried(1)).toBe(2)
})Typescript test
import {unless, isNil, inc} from 'rambda'
describe('R.unless', () => {
it('happy', () => {
const safeInc = unless<any, number>(isNil, inc)
const result = [safeInc(null), safeInc(1)]
result[0] // $ExpectType number
result[1] // $ExpectType number
})
it('it needs explicitly declared types', () => {
const safeInc = unless(x => x > 5, inc)
const result = safeInc(1)
result // $ExpectType number
})
})4 failed Ramda.unless specs
💥 Reason for the failure: Rambda library doesn't have
R.of
update
update<T>(index: number, newValue: T, list: ReadonlyArray<T>): T[]It returns a copy of list with updated element at index with newValue.
const index = 2
const newValue = 88
const list = [1, 2, 3, 4, 5]
const result = R.update(index, newValue, list)
// => [1, 2, 88, 4, 5]Try the above R.update example in Rambda REPL
All Typescript definitions
update<T>(index: number, newValue: T, list: ReadonlyArray<T>): T[];
update<T>(index: number, newValue: T): (list: ReadonlyArray<T>) => T[];R.update source
import { curry } from './curry'
function updateFn(
index, newValue, list
){
const arrClone = list.slice()
return arrClone.fill(
newValue, index, index + 1
)
}
export const update = curry(updateFn)Tests
import { update } from './update'
const list = [ 1, 2, 3 ]
test('happy', () => {
const newValue = 8
const index = 1
const result = update(
index, newValue, list
)
const curriedResult = update(index, newValue)(list)
const tripleCurriedResult = update(index)(newValue)(list)
const expected = [ 1, 8, 3 ]
expect(result).toEqual(expected)
expect(curriedResult).toEqual(expected)
expect(tripleCurriedResult).toEqual(expected)
})
test('list has no such index', () => {
const newValue = 8
const index = 10
const result = update(
index, newValue, list
)
expect(result).toEqual(list)
})Typescript test
import {update} from 'rambda'
describe('R.update', () => {
it('happy', () => {
const result = update(1, 0, [1, 2, 3])
result // $ExpectType number[]
})
})1 failed Ramda.update specs
💥 Reason for the failure: Ramda method accepts an array-like object
💥 Reason for the failure: Ramda method accepts an array-like object
var R = require('../../../../dist/rambda.js');
var eq = require('./shared/eq');
describe('update', function() {
it('accepts an array-like object', function() {
function args() {
return arguments;
}
eq(R.update(2, 4, args(0, 1, 2, 3)), [0, 1, 4, 3]);
});
});values
values<T extends object, K extends keyof T>(obj: T): T[K][]With correct input, this is nothing more than Object.values(obj). If obj is not an object, then it returns an empty array.
const obj = {a:1, b:2}
R.values(obj)
// => [1, 2]Try the above R.values example in Rambda REPL
All Typescript definitions
values<T extends object, K extends keyof T>(obj: T): T[K][];R.values source
import { type } from './type'
export function values(obj){
if (type(obj) !== 'Object') return []
return Object.values(obj)
}Tests
import { values } from './values'
test('happy', () => {
expect(values({
a : 1,
b : 2,
c : 3,
})).toEqual([ 1, 2, 3 ])
})
test('with bad input', () => {
expect(values(null)).toEqual([])
expect(values(undefined)).toEqual([])
expect(values(55)).toEqual([])
expect(values('foo')).toEqual([])
expect(values(true)).toEqual([])
expect(values(false)).toEqual([])
expect(values(NaN)).toEqual([])
expect(values(Infinity)).toEqual([])
expect(values([])).toEqual([])
})Typescript test
import {values} from 'rambda'
describe('R.values', () => {
it('happy', () => {
const result = values({
a: 1,
b: 2,
c: 3,
})
result // $ExpectType number[]
})
})view
view<T, U>(lens: Lens): (target: T) => UIt returns the value of lens focus over target object.
const lens = R.lensProp('x')
R.view(lens, {x: 1, y: 2}) //=> 1
R.view(lens, {x: 4, y: 2}) //=> 4Try the above R.view example in Rambda REPL
All Typescript definitions
view<T, U>(lens: Lens): (target: T) => U;
view<T, U>(lens: Lens, target: T): U;R.view source
const Const = x => ({
x,
map : fn => Const(x),
})
export function view(lens, target){
if (arguments.length === 1) return _target => view(lens, _target)
return lens(Const)(target).x
}when
when<T, U>(predicate: (x: T) => boolean, whenTrueFn: (a: T) => U, input: T): UAll Typescript definitions
when<T, U>(predicate: (x: T) => boolean, whenTrueFn: (a: T) => U, input: T): U;
when<T, U>(predicate: (x: T) => boolean, whenTrueFn: (a: T) => U): (input: T) => U;
when<T, U>(predicate: (x: T) => boolean): FunctionToolbelt.Curry<(whenTrueFn: (a: T) => U, input: T) => U>;R.when source
import { curry } from './curry'
function whenFn(
predicate, whenTrueFn, input
){
if (!predicate(input)) return input
return whenTrueFn(input)
}
export const when = curry(whenFn)Tests
import { add } from './add'
import { when } from './when'
const predicate = x => typeof x === 'number'
test('happy', () => {
const fn = when(predicate, add(11))
expect(fn(11)).toBe(22)
expect(fn('foo')).toBe('foo')
})Typescript test
import {when} from 'rambda'
const predicate = (x: number) => x > 2
const whenTrueFn = (x: number) => x + 2
describe('R.when', () => {
it('happy', () => {
const result = when(predicate, whenTrueFn, 1)
result // $ExpectType number
})
it('curry 1', () => {
const fn = when(predicate, whenTrueFn)
const result = fn(1)
result // $ExpectType number
})
it('curry 2 require explicit types', () => {
const fn = when<number, number>(predicate)(whenTrueFn)
const result = fn(1)
result // $ExpectType number
})
it('curry 3 require explicit types', () => {
const result = when<number, number>(predicate)(whenTrueFn, 1)
result // $ExpectType number
})
})where
where<T, U>(conditions: T, input: U): booleanIt returns true if all each property in conditions returns true when applied to corresponding property in input object.
const condition = R.where({
a : x => typeof x === "string",
b : x => x === 4
})
const input = {
a : "foo",
b : 4,
c : 11,
}
const result = condition(input)
// => trueTry the above R.where example in Rambda REPL
All Typescript definitions
where<T, U>(conditions: T, input: U): boolean;
where<T>(conditions: T): <U>(input: U) => boolean;
where<ObjFunc2, U>(conditions: ObjFunc2, input: U): boolean;
where<ObjFunc2>(conditions: ObjFunc2): <U>(input: U) => boolean;R.where source
export function where(conditions, input){
if (input === undefined){
return _input => where(conditions, _input)
}
let flag = true
for (const prop in conditions){
const result = conditions[ prop ](input[ prop ])
if (flag && result === false){
flag = false
}
}
return flag
}Tests
import { equals } from './equals'
import { where } from './where'
test('when true', () => {
const predicate = where({
a : equals('foo'),
b : equals('bar'),
})
expect(predicate({
a : 'foo',
b : 'bar',
x : 11,
y : 19,
})).toEqual(true)
})
test('when false', () => {
const predicate = where({
a : equals('foo'),
b : equals('baz'),
})
expect(predicate({
a : 'foo',
b : 'bar',
x : 11,
y : 19,
})).toEqual(false)
})Typescript test
import {where, equals} from 'rambda'
describe('R.where', () => {
it('happy', () => {
const input = {
a: 'foo',
b: 'bar',
x: 11,
y: 19,
}
const conditions = {
a: equals('foo'),
b: equals('bar'),
}
const result = where(conditions, input)
const curriedResult = where(conditions)(input)
result // $ExpectType boolean
curriedResult // $ExpectType boolean
})
})2 failed Ramda.where specs
💥 Reason for the failure: Ramba method looks inside
prototypeproperty
whereEq
whereEq<T, U>(condition: T, input: U): booleanIt will return true if all of input object fully or partially include rule object.
const condition = { a : { b : 1 } }
const input = {
a : { b : 1 },
c : 2
}
const result = whereEq(condition, input)
//=> trueTry the above R.whereEq example in Rambda REPL
All Typescript definitions
whereEq<T, U>(condition: T, input: U): boolean;
whereEq<T>(condition: T): <U>(input: U) => boolean;R.whereEq source
import { equals } from './equals'
import { filter } from './filter'
export function whereEq(condition, input){
if (arguments.length === 1){
return _input => whereEq(condition, _input)
}
const result = filter((conditionValue, conditionProp) =>
equals(conditionValue, input[ conditionProp ]),
condition)
return Object.keys(result).length === Object.keys(condition).length
}Tests
import { whereEq } from './whereEq'
test('when true', () => {
const condition = { a : 1 }
const input = {
a : 1,
b : 2,
}
const result = whereEq(condition, input)
const expectedResult = true
expect(result).toEqual(expectedResult)
})
test('when false', () => {
const condition = { a : 1 }
const input = { b : 2 }
const result = whereEq(condition, input)
const expectedResult = false
expect(result).toEqual(expectedResult)
})
test('with nested object', () => {
const condition = { a : { b : 1 } }
const input = {
a : { b : 1 },
c : 2,
}
const result = whereEq(condition)(input)
const expectedResult = true
expect(result).toEqual(expectedResult)
})
test('with wrong input', () => {
const condition = { a : { b : 1 } }
expect(() => whereEq(condition, null)).toThrowWithMessage(TypeError,
'Cannot read property \'a\' of null')
})Typescript test
import {whereEq} from 'rambda'
describe('R.whereEq', () => {
it('happy', () => {
const result = whereEq({a: {b: 2}}, {b: 2})
const curriedResult = whereEq({a: {b: 2}})({b: 2})
result // $ExpectType boolean
curriedResult // $ExpectType boolean
})
})2 failed Ramda.whereEq specs
💥 Reason for the failure: Ramba method looks inside
prototypeproperty | Rambda.equals doesn't support equality of functions
without
without<T>(matchAgainst: ReadonlyArray<T>, source: ReadonlyArray<T>): T[]It will return a new array, based on all members of source list that are not part of matchAgainst list.
const source = [1, 2, 3, 4]
const matchAgainst = [2, 3]
const result = R.without(matchAgainst, source)
// => [1, 4]Try the above R.without example in Rambda REPL
All Typescript definitions
without<T>(matchAgainst: ReadonlyArray<T>, source: ReadonlyArray<T>): T[];
without<T>(matchAgainst: ReadonlyArray<T>): (source: ReadonlyArray<T>) => T[];R.without source
import { includes } from './includes'
import { reduce } from './reduce'
export function without(matchAgainst, source){
if (source === undefined){
return _source => without(matchAgainst, _source)
}
return reduce(
(prev, current) =>
includes(current, matchAgainst) ? prev : prev.concat(current),
[],
source
)
}Tests
import { without } from './without'
test('should return a new list without values in the first argument ', () => {
const itemsToOmit = [ 'A', 'B', 'C' ]
const collection = [ 'A', 'B', 'C', 'D', 'E', 'F' ]
expect(without(itemsToOmit, collection)).toEqual([ 'D', 'E', 'F' ])
expect(without(itemsToOmit)(collection)).toEqual([ 'D', 'E', 'F' ])
})
test('ramda test', () => {
expect(without([ 1, 2 ])([ 1, 2, 1, 3, 4 ])).toEqual([ 3, 4 ])
})Typescript test
import {without} from 'rambda'
const itemsToOmit = ['A', 'B', 'C']
const collection = ['A', 'B', 'C', 'D', 'E', 'F']
describe('R.without', () => {
it('happy', () => {
const result = without(itemsToOmit, collection)
result // $ExpectType string[]
})
it('curried', () => {
const result = without(itemsToOmit)(collection)
result // $ExpectType string[]
})
})2 failed Ramda.without specs
💥 Reason for the failure: Ramda method act as a transducer | Ramda method pass to equals method
💥 Reason for the failure: Ramda method act as a transducer | Ramda method pass to equals method
var R = require('../../../../dist/rambda.js');
var eq = require('./shared/eq');
describe('without', function() {
it('can act as a transducer', function() {
eq(R.into([], R.without([1]), [1]), []);
});
it('has R.equals semantics', function() {
function Just(x) { this.value = x; }
Just.prototype.equals = function(x) {
return x instanceof Just && R.equals(x.value, this.value);
};
eq(R.without([0], [-0]).length, 1);
eq(R.without([-0], [0]).length, 1);
eq(R.without([NaN], [NaN]).length, 0);
eq(R.without([[1]], [[1]]).length, 0);
eq(R.without([new Just([42])], [new Just([42])]).length, 0);
});
});xor
xor(x: boolean, y: boolean): booleanconst result = [
xor(true, true),
xor(false, false),
xor(false, true),
]
// => [false, false, true]Try the above R.xor example in Rambda REPL
All Typescript definitions
xor(x: boolean, y: boolean): boolean;
xor(y: boolean): (y: boolean) => boolean;R.xor source
export function xor(a, b){
if (arguments.length === 1) return _b => xor(a, _b)
return Boolean(a) && !b || Boolean(b) && !a
}Tests
import { xor } from './xor'
test('compares two values with exclusive or', () => {
expect(xor(true, true)).toEqual(false)
expect(xor(true, false)).toEqual(true)
expect(xor(false, true)).toEqual(true)
expect(xor(false, false)).toEqual(false)
})
test('when both values are truthy, it should return false', () => {
expect(xor(true, 'foo')).toEqual(false)
expect(xor(42, true)).toEqual(false)
expect(xor('foo', 42)).toEqual(false)
expect(xor({}, true)).toEqual(false)
expect(xor(true, [])).toEqual(false)
expect(xor([], {})).toEqual(false)
expect(xor(new Date(), true)).toEqual(false)
expect(xor(true, Infinity)).toEqual(false)
expect(xor(Infinity, new Date())).toEqual(false)
})
test('when both values are falsy, it should return false', () => {
expect(xor(null, false)).toEqual(false)
expect(xor(false, undefined)).toEqual(false)
expect(xor(undefined, null)).toEqual(false)
expect(xor(0, false)).toEqual(false)
expect(xor(false, NaN)).toEqual(false)
expect(xor(NaN, 0)).toEqual(false)
expect(xor('', false)).toEqual(false)
})
test('when one argument is truthy and the other is falsy, it should return true', () => {
expect(xor('foo', null)).toEqual(true)
expect(xor(null, 'foo')).toEqual(true)
expect(xor(undefined, 42)).toEqual(true)
expect(xor(42, undefined)).toEqual(true)
expect(xor(Infinity, NaN)).toEqual(true)
expect(xor(NaN, Infinity)).toEqual(true)
expect(xor({}, '')).toEqual(true)
expect(xor('', {})).toEqual(true)
expect(xor(new Date(), 0)).toEqual(true)
expect(xor(0, new Date())).toEqual(true)
expect(xor([], null)).toEqual(true)
expect(xor(undefined, [])).toEqual(true)
})
test.skip('returns a curried function', () => {
expect(xor()(true)(true)).toEqual(false)
expect(xor()(true)(false)).toEqual(true)
expect(xor()(false)(true)).toEqual(true)
expect(xor()(false)(false)).toEqual(false)
})Typescript test
import {xor} from 'rambda'
describe('R.xor', () => {
it('happy', () => {
xor(true, false) // $ExpectType boolean
})
it('curry', () => {
xor(true)(false) // $ExpectType boolean
})
})1 failed Ramda.xor specs
💥 Reason for the failure: Ramda method support empty call of method
💥 Reason for the failure: Ramda method support empty call of method
var R = require('../../../../dist/rambda.js');
var eq = require('./shared/eq');
describe('xor', function() {
it('returns a curried function', function() {
eq(R.xor()(true)(true), false);
eq(R.xor()(true)(false), true);
eq(R.xor()(false)(true), true);
eq(R.xor()(false)(false), false);
});
});zip
zip<K, V>(x: ReadonlyArray<K>, y: ReadonlyArray<V>): KeyValuePair<K, V>[]It will return a new array containing tuples of equally positions items from both x and y lists.
The returned list will be truncated to match the length of the shortest supplied list.
const x = [1, 2]
const y = ['A', 'B']
R.zip(x, y)
// => [[1, 'A'], [2, 'B']]
// truncates to shortest list
R.zip([...x, 3], ['A', 'B'])
// => [[1, 'A'], [2, 'B']]Try the above R.zip example in Rambda REPL
All Typescript definitions
zip<K, V>(x: ReadonlyArray<K>, y: ReadonlyArray<V>): KeyValuePair<K, V>[];
zip<K>(x: ReadonlyArray<K>): <V>(y: ReadonlyArray<V>) => KeyValuePair<K, V>[];R.zip source
export function zip(left, right){
if (arguments.length === 1) return _right => zip(left, _right)
const result = []
const length = Math.min(left.length, right.length)
for (let i = 0; i < length; i++){
result[ i ] = [ left[ i ], right[ i ] ]
}
return result
}Tests
import { zip } from './zip'
const array1 = [ 1, 2, 3 ]
const array2 = [ 'A', 'B', 'C' ]
test('should return an array', () => {
const actual = zip(array1)(array2)
expect(actual).toBeInstanceOf(Array)
})
test('should return and array or tuples', () => {
const expected = [
[ 1, 'A' ],
[ 2, 'B' ],
[ 3, 'C' ],
]
const actual = zip(array1, array2)
expect(actual).toEqual(expected)
})
test('should truncate result to length of shorted input list', () => {
const expectedA = [
[ 1, 'A' ],
[ 2, 'B' ],
]
const actualA = zip([ 1, 2 ], array2)
expect(actualA).toEqual(expectedA)
const expectedB = [
[ 1, 'A' ],
[ 2, 'B' ],
]
const actualB = zip(array1, [ 'A', 'B' ])
expect(actualB).toEqual(expectedB)
})Typescript test
import {zip} from 'rambda'
describe('R.zip', () => {
it('happy', () => {
const array1 = [1, 2, 3]
const array2 = ['A', 'B', 'C']
const result = zip(array1)(array2)
result // $ExpectType KeyValuePair<number, string>[]
})
})zipObj
zipObj<T>(keys: ReadonlyArray<string>, values: ReadonlyArray<T>): { [index: string]: T }It will return a new object with keys of keys array and values of values array.
const keys = ['a', 'b', 'c']
R.zipObj(keys, [1, 2, 3])
//=> {a: 1, b: 2, c: 3}
// truncates to shortest list
R.zipObj(keys, [1, 2])
//=> {a: 1, b: 2}Try the above R.zipObj example in Rambda REPL
All Typescript definitions
zipObj<T>(keys: ReadonlyArray<string>, values: ReadonlyArray<T>): { [index: string]: T };
zipObj(keys: ReadonlyArray<string>): <T>(values: ReadonlyArray<T>) => { [index: string]: T };R.zipObj source
import { take } from './take'
export function zipObj(keys, values){
if (arguments.length === 1) return yHolder => zipObj(keys, yHolder)
return take(values.length, keys).reduce((
prev, xInstance, i
) => {
prev[ xInstance ] = values[ i ]
return prev
}, {})
}Tests
import { equals } from './equals'
import { zipObj } from './zipObj'
test('zipObj', () => {
expect(zipObj([ 'a', 'b', 'c' ], [ 1, 2, 3 ])).toEqual({
a : 1,
b : 2,
c : 3,
})
})
test('0', () => {
expect(zipObj([ 'a', 'b' ])([ 1, 2, 3 ])).toEqual({
a : 1,
b : 2,
})
})
test('1', () => {
expect(zipObj([ 'a', 'b', 'c' ])([ 1, 2 ])).toEqual({
a : 1,
b : 2,
})
})
test('ignore extra keys', () => {
const result = zipObj([ 'a', 'b', 'c', 'd', 'e', 'f' ], [ 1, 2, 3 ])
const expected = {
a : 1,
b : 2,
c : 3,
}
expect(equals(result, expected)).toBeTrue()
})Typescript test
import {zipObj} from 'rambda'
describe('R.zipObj', () => {
it('happy', () => {
const result = zipObj(['a', 'b', 'c', 'd', 'e', 'f'], [1, 2, 3])
result // $ExpectType { [index: string]: number; }
})
})CHANGELOG
5.13.0
Add
R.takeWhilemethodFix
R.lensPathissue when using string as path input. The issue was introduced when fixing Issue #524 in the previous release.
5.12.1
Close Issue #524 - wrong
R.assocPathwhen path includes numbersR.includesthrows on wrong input, i.e.R.includes(1, null)
5.12.0
Add
R.movemethodAdd
R.unionmethodClose Issue #519 -
ts-toolbeltneeds other type of export with--isolatedModulesflagChange
R.whenimplementation and typings to match those ofRamdaR.overandR.setuseR.curryinstead of manual curryingR.lensPathtypings support string as path, i.e.'a.b'instead of['a', 'b']R.equalsnow supports negative zero just likeRamda.equalsR.replaceusesR.curry
5.11.0
Forgot to export R.of because of wrong marker in files/index.d.ts
5.10.0
Close Issue #514 -
wrong R.length with empty string
Close Issue #511 - error in ts-toolbelt library
Close Issue #510 - R.clamp should throw if min argument is greater than max argument
PR #508 - add
R.ofDefinition of
R.curryare not same as those of@types/ramdaDefinitions of
R.eitheris same as that ofR.bothDefinitions of
R.ifElseno longer useanytypeDefinition of
R.flattenrequires passing type for the outputFix definition of
R.propOr,R.dissocFix curried definitions of
R.take,R.takeLast,R.dropandR.dropLast5.9.0
R.pickAlldefinition allows passing string as path to search.R.propEqdefinition is now similar to that in@types/ramda.R.nonematchesR.allimplementation and pass index as second argument to predicate input.R.reduce- drop support for object as iterable. Now it throws the same error as Ramda. Also instead of returning the initial value when iterable isundefined, now it throws.
Add index as additional argument to the Typescript definitions of the following methods:
R.all
R.find
R.findLast
R.findIndex
R.findLastIndex
5.8.0
Add R.mergeAll
Add R.mergeDeepRight
Add R.mergeLeft
Add R.partition
Add R.pathEq
Add R.tryCatch
Add R.unless
Add R.whereEq
Add R.where
Add
R.lasttyping for empty array5.7.0 Revert PR #469 as
R.currywas slow | Also nowR.flipthrows if arity is greater than or equal to 55.6.3 Merge several PRs of @farwayer
PR #482 - improve
R.forEachperformance by not usingR.mapPR #485 - improve
R.mapperformancePR #482 - improve
R.reduceperformanceFix missing high arity typings for
R.compose/pipeR.mergedefinitions match those of@types/ramdaRemove
distfolder from Rambda repo5.6.2
Close Issue #476 - typesafe R.propEq definitions
Approve PR #477 - fix R.groupWith when list length is 1
- 5.6.1
Update ts-toolbelt files as now there is update pipeline for it.
Approve PR #474 - intruduce internal isArray helper
- 5.6.0
Approve PR #469 - R.flip supports any arity | implement R.curry with R.curryN add R.applySpec
- 5.5.0
Close Issue #464 - R.flip should handle functions with arity above 2
Close Issue #468 - fs-extra should be dev dependency as it was wrongly added as production dependency in 5.2.0
R.flip typings now match @types/ramda typings
Add R.hasPath method
Add R.mathMod typings
- 5.4.3
Fix R.omit typings
- 5.4.2
Fix R.pick typings
Close Issue #460 -
R.pathsshould be curried
- 5.4.1
Close Issue #458 - wrong
R.propIstyping
- 5.4.0
Close Issue #408 - add
R.chain
- 5.3.0
Close Issue #430 - add
R.when
Also restore R.converge, R.findLast, R.findLastIndex and R.curryN as I have forgotten to export them when releasing 5.2.0.
- 5.2.1
Fix Typescript comment for every method
- 5.2.0
Release new documentation site
Ramda repo now holds all Rambdax methods and tests
- 5.1.1
Add R.converge and R.curryN from PR #412
Close Issue #410 - wrong implementation of R.groupWith
Close Issue #411 - change the order of declared R.map typings rules
- 5.0.0
Move R.partialCurry to Rambdax(reason for major bump).
Use new type of export in Typescript definitions.
Approve PR #381 - add R.applySpec
- 4.6.0
Approve PR #375 - add lenses(Thank you @synthet1c)
Add R.lens
Add R.lensIndex
Add R.lensPath
Add R.lensProp
Add R.over
Add R.set
Add R.view
Sync with Ramda 0.27
Add R.paths
Add R.xor
Close Issue #373
Add R.cond
4.5.0 Add
R.clamp4.4.2 Improve
R.propOrtypings4.4.1 Make
R.rejecthas the same typing asR.filter4.4.0 Several changes:
Close Issue #317 - add R.transpose
Close Issue #325 - R.filter should return equal values for bad inputs null and undefined
Approve suggestion for R.indexBy to accept string not only function as first argument.
Edit of R.path typings
4.2.0 Approve PR #314 - add
R.and4.1.1 Add missing typings for
R.slice4.1.0 Add
R.findLastandR.findLastIndex4.0.2 Fix
R.isEmptywrong behaviour compared to the Ramda method4.0.1 Approve PR #289 - remove console.log in
R.valuesmethod4.0.0 Multiple breaking changes as Rambda methods are changed in order to increase the similarity between with Ramda
Add to Differences:
R.type can return 'NaN'
R.compose doesn't pass `this` context
R.clone doesn't work with number, booleans and strings as inputAll breaking changes:
-- R.add works only with numbers
-- Fix R.adjust which had wrong order of arguments
-- R.adjust works when index is out of bounds
-- R.complement support function with multiple arguments
-- R.compose/pipe throws when called with no argument
-- R.clone works with Date value as input
-- R.drop/dropLast/take/takeLast always return new copy of the list/string
-- R.take/takeLast return original list/string with negative index
-- R.equals handles NaN and RegExp types
-- R.type/R.equals supports new Boolean/new Number/new Date/new String expressions
-- R.has works with non-object
-- R.ifElse pass all arguments
-- R.length works with bad input
-- R.propEq work with bad input for object argument
-- R.range work with bad inputs
-- R.times work with bad inputs
-- R.reverse works with strings
-- R.splitEvery throws on non-positive integer index
-- R.test throws just like Ramda when first argument is not regex
-- R.values works with bad inputs
-- R.zipObj ignores extra keys
- 3.3.0
This is pre 4.0.0 release and it contains all of the above changes
Close issue #287 - ts-toolbelt directory was changed but not reflected in files property in package.json
- 3.2.5
Close issue #273 - ts-toolbelt needs other type of export when isolatedModules TypeScript property
Close issue #245 - complete typings tests for methods that have more specific Typescript definitions
3.2.1 Fast fix for issue #273 - messed up typings
3.2.0 There are several changes:
Close issue #263 - broken curry typing solved by ts-toolbelt local dependency.
Add R.partialCurry typings.
Approve PR #266 that adds R.slice method.
3.1.0 This might be breaking change for Typescript users, as very different definitions are introduced. With the previous state of the definitions, it was not possible to pass
dtslinttypings tests.R.eitherandR.bothsupports multiple arguments as they should.Several methods added by @squidfunk -
R.assocPath,R.symmetricDifference,R.intersperse,R.intersectionandR.difference3.0.1 Close issue #234 - wrong curry typing
3.0.0 Deprecate
R.contains, whileR.includesis now following Ramda API(it usesR.equalsfor comparision)2.14.5
R.withoutneeds currying2.14.4 Close issue #227 - add index as third argument of
R.reducetypings2.14.2 Use
R.currywithR.reduceas manual curry there didn't work as expected.2.14.1 Fix wrong typescript with
R.head- PR #228 pushed by @tonivj52.14.0 Add
R.groupWithby @selfrefactor | AddR.propOr,R.mathMod,R.mean,R.median,R.negate,R.productby @ku8ar2.12.0 Add
R.propIs- PR #213 and addR.sum- issue #2072.11.2 Close Rambdax issue #32 - wrong
R.typewhen function is input2.11.1 Approve PR #182 - Changed typings to allow object as input to
R.forEachandR.map2.11.0 Approve PR #179 -
R.adjusthandles negative index;R.alldoesn't needR.filter2.10.2 Close issue #175 - missing typescript file
2.10.0 Approve huge and important PR #171 submitted by @helmuthdu - Add comments to each method, improve Typescript support
2.9.0
R.toPairsandR.fromPairs2.8.0 Approve PR #165
R.clone2.7.1 expose
src| Discussed at issue #1472.7.0 Approve PR #161
R.isEmpty2.6.0
R.map,R.filterandR.forEachpass original object to iterator as third argument | Discussed at issue #1472.5.0 Close issue #149 Add
R.partial|R.typehandlesNaN2.4.0 Major bump of
Rollup; Stop building for ES52.3.1 Close issue #90 | Add string type of path in
R.pathOr2.3.0 Close issue #89 | Fix missing
NumberTS definition inR.type2.2.0
R.defaultToaccepts indefinite number of input arguments. So the following is valid expression:const x = defaultTo('foo',null, null, 'bar')2.1.0 Restore
R.zipusing WatermelonDB implementation.2.0.0 Major version caused by removing of
R.zipandR.addIndex. Issue #85 rightfully finds that the implementation ofR.addIndexis not correct. This led to removing this method and also ofR.zipas it had depended on it. The second change is thatR.map,R.filterare passing array index as second argument when looping over arrays. The third change is thatR.includeswill returnfalseif input is neigherstringnorarray. The previous behaviour was to throw an error. The last change is to increase the number of methods that are passing index as second argument to the predicate function.1.2.6 Use
srcfolder instead ofmodules1.2.5 Fix
omittyping1.2.4 Add missing Typescript definitions - PR#82
1.2.2 Change curry method used across most of library methods
1.2.1 Add
R.assoc| fix passingundefinedtoR.mapandR.mergeissue #771.2.0 Add
R.min,R.minBy,R.max,R.maxBy,R.nthandR.keys1.1.5 Close issue #74
R.zipObj1.1.4 Close issue #71 CRA fail to build
rambda1.1.2 Approve PR #67 use
babel-plugin-annotate-pure-calls1.1.1 Approve PR #66
R.zip1.1.0
R.composeaccepts more than one input argument issue #651.0.13 Approve PR #64
R.indexOf1.0.12 Close issue #61 make all functions modules
1.0.11 Close issue #60 problem with babelrc
1.0.10 Close issue #59 add R.dissoc
1.0.9 Close issue #58 - Incorrect
R.equals1.0.8
R.mapandR.filterpass object properties when mapping over objects1.0.7 Add
R.uniqWith1.0.6 Close issue #52 - ES5 compatible code
1.0.5 Close issue #51
1.0.4 Close issue #50 - add
R.pipetypings1.0.3
R.ifElseaccept also boolean as condition argument1.0.2 Remove
typedDefaultToandtypedPathOr| AddR.pickAllandR.none1.0.0 Major change as build is now ES6 not ES5 compatible (Related to issue #46)| Making
Rambdafully tree-shakeable| Edit Typescript definition0.9.8 Revert to ES5 compatible build - issue #46
0.9.7 Refactor for
Rolluptree-shake | RemoveR.padEndandR.padStart0.9.6 Close issue #44 -
R.reversemutates the array0.9.5 Close issue #45 - invalid Typescript typings
0.9.4 Add
R.rejectandR.without(PR#41 PR#42) | Remove 'browser' field inpackage.jsondue to Webpack bug 46740.9.3 Add
R.forEachandR.times0.9.2 Add
Typescriptdefinitions0.9.1 Close issue #36 - move current behaviour of
defaultToto a new methodtypedDefaultTo; makedefaultTofollow Ramda spec; addpathOr; addtypedPathOr.0.9.0 Add
R.pipePR#350.8.9 Add
R.isNil0.8.8 Migrate to ES modules PR33 | Add R.flip to the API | R.map/filter works with objects
0.8.7 Change
WebpackwithRollup- PR290.8.6 Add
R.tapandR.identity0.8.5 Add
R.all,R.allPass,R.both,R.eitherandR.complement0.8.4 Learning to run
yarn testbeforeyarn publishthe hard way0.8.3 Add
R.always,R.TandR.F0.8.2 Add
concat,padStart,padEnd,lastIndexOf,toString,reverse,endsWithandstartsWithmethods0.8.1 Add
R.ifElse0.8.0 Add
R.not,R.includes| Take string as condition forR.pickandR.omit0.7.6 Fix incorrect implementation of
R.values0.7.5 Fix incorrect implementation of
R.omit0.7.4 issue #13 - Fix
R.curry, which used to return incorrectlyfunctionwhen called with more arguments0.7.3 Close issue #9 - Compile to
es2015; Approve PR #10 - addR.addIndexto the API0.7.2 Add
Promisesupport forR.type0.7.1 Close issue #7 - add
R.reduceto the API0.7.0 Close issue #5 - change name of
currytopartialCurry; add new methodcurry, which works just like Ramda'scurry0.6.2 Add separate documentation site via
docsify
Additional info
Most influential contributors
- @farwayer
- @thejohnfreeman
- @helmuthdu
- @jpgorman
- @ku8ar
- @romgrk
- @squidfunk
- @synthet1c
- @vlad-zhukov
- @WhoAteDaCake
Rambda references
Links to Rambda