FunctionalScript

FunctionalScript is a pure functional programming language and a strict subset of ECMAScript/JavaScript. It's inspired by

• JSON, as a subset of JavaScript. JSON is also a subset of FunctionalScript.
• asm.JS/WebAssembly, as a subset of JavaScript.
• TypeScript, as a superset of JavaScript.

Try FunctionalScript here.

Create a new FunctionalScript repository on GitHub here.

To install this repository as a library use:

npm install -S github:functionalscript/functionalscript

1. Design Principles

In FunctionalScript:

• Any module is a valid JavaScript module
• A module can't depend on non FunctionalScript module.
• A module can contain only pure functional statements. There are no exceptions to this rule, such as unsafe code in Rust or C#.
• It also has no standard library, only a safe subset of standard JavaScript API is allowed.

2. Outlines

2.1. Module Ecosystem

FunctionalScript uses Common.JS conventions as a module ecosystem. For example,

const thirdPartyModule = require('third-party-package/module')

const result = thirdPartyModule.someFunction('hello')

2.2. Packages

FunctionalScript uses a package.json file to define a package. This file is compatible with Node.js package.json. The prefered way to refence dependencies is to use a GitHub URL. An example of dependencies in a package.json file:

{
   ...
   "dependencies": {
      "third-party-package": "github:exampleorg/thirdpartypackage"
   }
   ...
}

2.2. Module Structure

A module is a file with the .js extention. It contains three parts: references to other modules, definitions, and exports. For example

./first.js

// 1. references
const math = require('math')

// 2. definitions
const myConst = 42
const addition = a => b => a + b
const add42 = addition(42)
const _10digitsOfPi = math.calculatePi(10)

// 3. exports
module.exports = {
   addition,
   add42,
   _10digitsOfPi,
}

./second.js

// 1. references
const first = require('./first.js')

const _42plus7 = first.add42(7)

2.3. References To Other Modules

The format of references is const ANYNAME = require('PATH_TO_A_MODULE'). For example

const math = require('math')
const algebra = require('math/algebra')
const localFile = require('../some-directory/some-file.js')

2.4. Definitions

The format of defintions is const NAME = EXPRESSION, where the EXPRESSION is a subset of JavaScript expressions.

const myConst = 42
const functionDouble = a => a * 2
const structure = { name: "John", surname: "Smith" }
const array = [1, 2, 3]
const nestedStructure = { 
   address: undefined, 
   serialNumber: "123-45-78", 
   sum: 14 + myConst + functionDouble(4),
   moreInfo: { 
      name: "Ivan",
      surname: "Terrible",
   } 
}

2.5. Exports

The format of exports is module.exports = { A_LIST_OF_EXPORTED_DEFINITIONS }. There should be only one module.exports at the end of a FunctionalScript file. For example

module.exports = {
   nestedStructure,
   array,
   structure,
}