A monad for time-dependant values, providing explicit effects for delayed computations, latency, etc.
Future(a, b) structure 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][CPS] form of programming, in order to be able to compose and sequence time-dependent effects using the generic and powerful monadic operations.
var Future = require'data.future'var fs = require'fs'// read : String -> Future(Error, Buffer)returnfsreadFilepathif error rejecterrorelse resolvedata// decode : Future(Error, Buffer) -> Future(Error, String)return buffermapreturn atoString'utf-8'var intro = decoderead'intro.txt'var outro = decoderead'outro.txt'// You can use `.chain` to sequence two asynchronous actions, and// `.map` to perform a synchronous computation with the eventual// value of the Future.var concatenated = introchainreturn outromapreturn a + b// But the implementation of Future is pure, which means that you'll// never observe the effects by using `chain` or `map` or any other// method. The Future just records the sequence of actions that you// wish to observe, and defers the playing of that sequence of actions// for your application's entry-point to call.//// To observe the effects, you have to call the `fork` method, which// takes a callback for the rejection, and a callback for the success.concatenatedforkthrow errorconsole.logdata
The easiest way is to grab it from NPM. If you're running in a Browser environment, you can use [Browserify]
$ npm install data.future
If you're not using NPM, [Download the latest release][release], and require
var Future = require'data.future'
[Download the latest release][release], and require the
[Download the latest release][release], and load the
file. The properties are exposed in the global
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/data.future.git $ cd data.future $ npm install $ make bundle
This will generate the
dist/data.future.umd.js file, which you can load in
You can [read the documentation online][docs] 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/index.html in your browser.
This library assumes an ES5 environment, but can be easily supported in ES3 platforms by the use of shims. Just include [es5-shim] :)
Copyright (c) 2013-2014 Quildreen Motta.
Released under the MIT licence.[Fantasy Land]: https://github.com/fantasyland/fantasy-land [Browserify]: http://browserify.org/ [Git]: http://git-scm.com/ [Make]: http://www.gnu.org/software/make/ [Node.js]: http://nodejs.org/ [es5-shim]: https://github.com/kriskowal/es5-shim [docs]: http://folktale.github.io/data.future [CPS]: http://matt.might.net/articles/by-example-continuation-passing-style/ [release]: https://github.com/folktale/data.future/releases/download/v2.3.0/data.future-2.3.0.tar.gz