monads.future

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

npm install monads.future
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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.

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