immutable-ext

fantasyland extensions for immutablejs

Install

npm install immutable-ext

What is this?

In addition to the Functor, Foldable, and Monad functions, we now have:

  • Monoid
  • Applicative (list only right now)
  • Traversable

Plus stuff that builds off of reduce like foldMap. Please contribute/complain as you want/need things.

Examples

We can now traverse without messing with Array or Object:

  1.   const { List, Map } = require('immutable-ext')
  2.   const Task = require('data.task')
  3.   const IO = require('fantasy-io')
  6.   // Given Http.get :: String -> Task Error Blog
  8.   List.of('/blog/1', '/blog/2')
  9.     .traverse(Task.of, Http.get)
  10.     .fork(console.error, console.log)
  11.   // List(Blog, Blog)
  14.   Map({home: "<div>homepage</div>", faq: "<p>ask me anything</p>"})
  15.     .traverse(IO.of, (v, k) => new IO(v => $('body').append(v)))
  17.   // IO(Map({home: "[dom]", faq: "[dom]"})

We can fold stuff down

  1. const {Disjunction, Additive} = require('fantasy-monoids')
  3. List.of([1,2,3], [4,5,6]).fold([])
  4. //[1,2,3,4,5,6]
  6. Map({a: "hidy", b: "hidy", c: "ho"}).fold("")
  7. // "hidyhidyho"
  10. List.of(Map({a: Additive(1), b: Disjunction(true), c: "son", d: [1], e: 'wut'}),
  11.         Map({a: Additive(2), b: Disjunction(false), c: "ofa", d: [2]}),
  12.         Map({a: Additive(3), b: Disjunction(false), c: "gun", d: [3]})).fold(Map.empty),
  14. // Map({a: Additive(6), b: Disjunction(true), c: "sonofagun", d: [1,2,3], e: 'wut'})))

foldMap some things

  1. List.of(1,2,3,4).foldMap(Additive, Additive.empty)
  2. // Additive(10)
  4. Map({a: true, b: false}).foldMap(Disjunction, Disjunction.empty)
  5. // Disjunction(true)

We can ap to get us some list comprehensions

  1. List.of(x => y => x + y)
  2.     .ap(List.of('a', 'b', 'c'))
  3.     .ap(List.of('+', '-'))
  5. // List('a+', 'a-', 'b+', 'b-', 'c+', 'c-')