something something

go crazy? don't mind if i do...

a little asynchronous functional programming library.

• why?
• how?
• what?

why?

There are plenty of collections libraries out there (think underscore, lodash, etc) and plenty of asynchronous ones (async comes to mind), but none of them seem to support asynchronous mapping over plain old JavaScript objects. So I wrote this for that use-case, and while I was at it generalized it to handle both objects and arrays.

how?

Use the package manager of your choice to install. We support

# npm 
npm install --save something-something
 
# component 
component install couchand/something-something
 
# bower 
bower install something-something

Require it in your project and start asynchronizing.

__ = require 'something-something'
 
double = (value, cb) -> cb null, value * 2
ba_s = (key, value, cb) -> cb null, /ba./.test key
 
original =
  foo: 1
  bar: 2
  baz: 3
 
__.map original, double, (error, doubled) ->
  __.filter doubled, ba_s, (error, result) ->
    assert Object.keys(result).length is 2
    assert result.bar is 4
    assert result.baz is 6

Simple, right?

what?

The standard functional collections methods are here.

• map
• filter
• any
• all
• what, no reduce?

All methods work equally well for arrays and objects.

map

__.map(collection, iterator, [complete])

collection = Array
           | Object
iterator   = (value, cb) -> result
           | (key, value, cb) -> result
           | (key, value, collection, cb) -> result
complete   = (error, results) ->

Standard map function, known in some circles as collect. The iterator function is called for each element in the collection. Its behavior is guessed from the airity of the function, so don't try any fancy business with arguments here.

The complete callback is called with the results collection once every iteration is complete. If any iteration callsback with an error the map immediately fails, calling back with that error.

filter

__.filter(collection, predicate, [complete])

collection = Array
           | Object
predicate  = (value, cb) -> Boolean
           | (key, value, cb) -> Boolean
           | (key, value, collection, cb) -> Boolean
complete   = (error, results) ->

Standard filter function, also known as select. The predicate is called for each element in the collection. Again its behavior is assumed based on the airity. The result is coerced to a Boolean.

The complete callback is called with the filtered results once every predicate is complete. If any predicate callsback with an error the filter immediately fails, calling back with that error.

any

__.any(collection, predicate, [complete])

collection = Array
           | Object
predicate  = (value, cb) -> Boolean
           | (key, value, cb) -> Boolean
           | (key, value, collection, cb) -> Boolean
complete   = (error, result) ->

Short-circuiting boolean or (aka some). Callsback true as soon as any of the predicates callsback true. Callsback false if every predicate callsback false.

Callsback with an error if any predicate callsback in error before one callsback true. This means it swallows some errors and not others, which may not be desirable.

all

collection = Array
           | Object
predicate  = (value, cb) -> Boolean
           | (key, value, cb) -> Boolean
           | (key, value, collection, cb) -> Boolean
complete   = (error, result) ->

Short-circuiting boolean and (aka every). Callsback false as soon as a single predicate callsback false. Callsback true if every predicate callsback true.

Callsback with an error if any predicate callsback in error before one callsback false. This means it swallows some errors and not others, which may not be desirable.

what, no reduce?

This library is about eagerly evaluating a sequence of asynchronous callbacks massively parallel. Reduce is by nature a series algorithm. If you think there's a good way to write reduce in the same style as the other methods please do submit a pull request.

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