https://github.com/allouis/functor

https://github.com/allouis/functor

Last synced: 24 days ago
JSON representation

• Host: GitHub
• URL: https://github.com/allouis/functor
• Owner: allouis
• Created: 2015-03-25T14:34:04.000Z (over 9 years ago)
• Default Branch: master
• Last Pushed: 2015-06-23T12:07:36.000Z (over 9 years ago)
• Last Synced: 2024-10-05T22:45:54.384Z (about 1 month ago)
• Language: JavaScript
• Size: 145 KB
• Stars: 4
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

Awesome Lists containing this project

README

        
# functor

## Usage

```javascript

var functor = require('functor');

var fmap = functor.fmap;

// We can define fmap methods on predefined types using the functor function

// N.B. this does not affect any prototype chains or modify external objects

functor(Promise, function(fn, functor){

  // functor here is the promise instance

  return functor.then(fn);

});

functor(Array, function(fn, functor){

  return functor.map(fn);

});

// fmap will also look for an fmap method on the object

function Nothing() {}

Nothing.prototype.fmap = function () { return Nothing() };

function Just(val) {

  this.val = val;

}

Just.prototype.fmap = function (fn) { return Maybe(fn(this.val)) }

function Maybe(val) {

  return val == null ? Nothing() : Just(val)

}

function logName(obj) {

  console.log(obj.name);

  return obj;

}

var somePromise = getUserFromServer();

// this will log out the name at some point;

fmap(logName, somePromise); // returns a new functor, of same type (Promise);

var me = {name: 'fabien'}

// this will log out "fabien"

fmap(logName, Maybe(me)); // returns new functor (Just)

var you;

// this doesn't log out anything, nor does it throw a cannot read property name of null

fmap(logName, Maybe(you)); // returns new functor (Nothing)

```