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monads.future

A monad for time-dependant values, providing explicit effects for delayed computations, latency, etc.

monads.future

Build Status NPM version Dependencies Status experimental

The Future(a, b) monad represents values that depend on time. This allows one to model time-based effects explicitly, such that one can have full knowledge of when they're dealing with delayed computations, latency, or anything that can not be computed immediately.

A common use for this monad is to replace the usual Continuation-Passing Style form of programming, in order to be able to compose and sequence time-dependent effects using the generic and powerful monadic operations.

Example

var Future = require('monads.future')
 
function get(url) {
  return new Future(function(resolve, reject) {
    var request = new XMLHttpRequest()
    request.onload = function() {
      if (!/2\d\d/.test(this.status))  reject(this.responseText)
      else                             resolve(this.responseText)
    }
    request.open("get", url, true)
    request.send()
  })
}
 
var t1 = get('/something')
var t2 = get('/other')
 
var t3 = t1.map(function(a) {
           t2.map(function(b) {
             return a + b
           })
         })
 
t3.chain(function(a) {
  console.log(a)
})

Installing

The easiest way is to grab it from NPM. If you're running in a Browser environment, you can use Browserify

$ npm install monads.future

Using with CommonJS

If you're not using NPM, Download the latest release, and require the monads.future.umd.js file:

var Future = require('monads.future')

Using with AMD

Download the latest release, and require the monads.future.umd.js file:

require(['monads.future'], function(Future) {
  ( ... )
})

Using without modules

Download the latest release, and load the monads.future.umd.js file. The properties are exposed in the global Future object:

<script src="/path/to/monads.future.umd.js"></script>

Compiling from source

If you want to compile this library from the source, you'll need Git, Make, Node.js, and run the following commands:

$ git clone git://github.com/folktale/monads.future.git
$ cd monads.future
$ npm install
$ make bundle

This will generate the dist/monads.future.umd.js file, which you can load in any JavaScript environment.

Documentation

You can read the documentation online or build it yourself:

$ git clone git://github.com/folktale/monads.maybe.git
$ cd monads.maybe
$ npm install
$ make documentation

Then open the file docs/literate/index.html in your browser.

Platform support

This library assumes an ES5 environment, but can be easily supported in ES3 platforms by the use of shims. Just include es5-shim :)

Licence

Copyright (c) 2013 Quildreen Motta.

Released under the MIT licence.