Package Exports

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 (imj) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

Readme

imj

Not fastest but powerful immutable helper

Simple update

import imj from "imj";

const Increase = imj({
  count: ({ value }) => value + 1
});
const Decrease = imj({
  count: ({ value }) => value - 1
});
Increase({ count: 1 }); // { count: 2 }
Decrease({ count: 1 }); // { count: 0 }

Retrieve argument values

import imj from "imj";

const Increase = imj({
  count: ({ value, $1 = 1 }) => value + $1
});

Increase({ count: 1 }); // { count: 2 }
Increase({ count: 1 }, 2); // { count: 3 }

Update array

import imj from "imj";

const AddTodo = imj({
  // map second argument to $text and the third to $done
  $args: "$text $done",
  todos: ({ $text, $done, push }) =>
    // push new item to todos array
    push({ text: $text, done: $done })
});

AddTodo({ todos: [{ text: "first", done: false }] }, "second", true);
// { todos: [ { text: 'first', done: false }, { text: 'second', done: true } ] }

Update specified items in array

import imj from "imj";

const ToggleDoneSpecs = { done: ({ toggle }) => toggle() };

const ToggleTodoByIndex = imj({
  $args: "$index",
  // create custom specs
  $extend: ({ $index }) => ({
    todos: {
      // toggle done property of specified item ($index)
      [$index]: ToggleDoneSpecs
    }
  })
});

const ToggleOneTodoByText = imj({
  $args: "$text",
  todos: {
    // update first match only
    $one: ({ value, $text }) =>
      value.text === $text
        ? // return specs for matched item
          ToggleDoneSpecs
        : // unless do nothing
          null
  }
});

const ToggleAllTodoByText = imj({
  $args: "$text",
  todos: {
    // update all
    $many: ({ value, $text }) =>
      value.text === $text
        ? // return specs for matched item
          ToggleDoneSpecs
        : // unless do nothing
          null
  }
});

const ToggleAll = imj({
  todos: {
    $many: ToggleDoneSpecs
  }
});

Simple redux reducer

import imj from "imj";

const IncreaseAction = 1;
const DecreaseAction = 2;
const reducer = imj({
  $when: [
    "$1.type",
    {
      [IncreaseAction]: {
        count: ({ value, $1: { payload = 1 } }) => value + payload
      },
      [DecreaseAction]: {
        count: ({ value, $1: { payload = 1 } }) => value - payload
      }
    }
  ]
});
reducer({ count: 1 }, { type: IncreaseAction }); // { count: 2 }
reducer({ count: 1 }, { type: IncreaseAction, payload: 2 }); // { count: 3 }
reducer({ count: 1 }, { type: DecreaseAction }); // { count: 0 }
reducer({ count: 1 }, { type: DecreaseAction, payload: 2 }); // { count: -1 }

Other implementation

import imj from "imj";

const IncreaseAction = 1;
const DecreaseAction = 2;
const reducer = imj({
  // define named $when
  $when_increase: [
    "$1.type",
    IncreaseAction,
    {
      count: ({ value, $1: { payload = 1 } }) => value + payload
    }
  ],
  $when_decrease: [
    "$1.type",
    DecreaseAction,
    {
      count: ({ value, $1: { payload = 1 } }) => value - payload
    }
  ]
});