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LambdaJS

The full ECMAScript API done a functional way.

RULES

  1. The data comes last. E.g: str.method(arg) -> method(arg, str)
  2. Everything is curried
  3. Functions with optional arguments are split into two functions. One with _ at the end that takes the options. E.g: indexOf(x,str) & indexOf_(x,y,str)
  4. Every function is pure

Thanks so much to @casperin and @eschmitt for doing a ton of the work on this though isn't not visible in the contributors.

DOCS

docs

USAGE

There is an expose() method to "mix in" to the global namespace if desired.

In the browser

<script src="dist/lambda.browser.js"></script>
<script>LambdaJS.expose(window);</script>

or

define(['dist/lambda.amd.js'], function(Ljs){
	
});

In node

npm install lambdajs
var ljs = require('lambdajs');

or

require('lambdajs').expose(global);

MOTIVATION

Let's say you want to replace "-" for "/" in a js function. Typically you'd have to do:

var dashesForSlashes = function(str) {
  return str.replace(/-/g, '/');
}

This has some issues.

  • We had to name a temporary variable str
  • We had to write some "glue code" - a full function(){} complete with return
  • We are dependent upon the str to be able to call replace

In functional "point free" style we don't need to grab a hold of our data to be able to write new functions. In this case, by "data" I mean the string.

LambdaJS let's us write something like this:

var dashesForSlashes = replace(/-/g, '/');

This is very useful when dealing with compose

var f = compose(toUpperCase, replace(/-/g, '/'))
f("hi-guys") //=> HI/GUYS

Another issue is, in standard javascript, if you call reverse on an array, you will permanently alter the array:

var users = ['Alex', 'Sam', 'Pat']
users.reverse(); //=> ['Pat', 'Sam' 'Alex']
users //=> ['Pat', 'Sam' 'Alex']

That can be quite surprising when you go to display users in a different spot of your app and they are out of order.

LambdaJS makes all the built-in functions "pure", meaning there is no side-effects or mutation.

var users = ['Alex', 'Sam', 'Pat']
reverse(users); //=> ['Pat', 'Sam' 'Alex']
users //=> [['Alex', 'Sam', 'Pat']

If you're interested in learning more about currying and composition, I gave a talk on this subject a little while ago: Hey underscore, you're doing it wrong!

ROADMAP (help if ya want!):