A practical functional library for Javascript programmers.


Using this library should feel as much like using Javascript as possible. Of course it's functional Javascript, but we're not introducing lambda expressions in strings, we're not borrowing consed lists, we're not porting over all of the Clojure functions.

Our basic data structures will be normal Javascript objects, and our usual collections will be Javascript arrays. We will not try to reach the point where all the functions have only zero, one, or two arguments. We will certainly try to keep some of the normal features of Javascript that seem to be unusual in functional languages, including variable length function signatures and functions as objects with properties.

Ramda will never be a drop-in replacement for Underscore (or LoDash, or even a drop-in-and-mechanically-switch-the-parameter-order-everywhere replacement.) It is intended to work with a different style of coding. Functional programming is in good part about immutable objects and side-effect free functions. While Ramda does not expect to do anything to enforce that style, its code should always work to make that style as frictionless as possible.

As much as we can, we would like the implementation to be both clean and elegant. But the API is king: we will sacrifice a great deal of implementation elegance for even a slightly cleaner API.

Unlike the developers of that silly-named Eweda project, though, this one will focus also on performance, striving for a reliable and quick implementation over any notions of functional purity.

To use with node:

$ npm install ramda

Then in the console:

var ramda = require('ramda');

To use directly in the browser:

<script src="path/to/yourCopyOf/ramda.js"></script>

or the minified version:

<script src="path/to/yourCopyOf/ramda.min.js"></script>

or from a CDN, either cdnjs:

<script src="//cdnjs.cloudflare.com/ajax/libs/ramda/0.8.0/ramda.min.js"></script>

or one of the below links from jsDelivr:

<script src="//cdn.jsdelivr.net/ramda/0.8.0/ramda.min.js"></script>
<script src="//cdn.jsdelivr.net/ramda/0.8/ramda.min.js"></script>
<script src="//cdn.jsdelivr.net/ramda/latest/ramda.min.js"></script>

(note that using latest is taking a significant risk that ramda API changes could break your code.)

These script tags add the variable ramda on the browser's global scope.

Or you can inject ramda into virtually any unsuspecting web site using this bookmarklet:

javascript:(function(){var el=document.createElement('div'),b=document.getElementsByTagName('body')[0];msg='';el.style.position='fixed';el.style.height='32px';el.style.width='220px';el.style.marginLeft='-110px';el.style.top='0';el.style.left='50%';el.style.padding='5px 10px';el.style.zIndex=1001;el.style.fontSize='12px';el.style.color='#222';el.style.backgroundColor='#f99';if(typeof ramda!='undefined'){msg='This page already using ramda v'+ramda.version;return showMsg()}function getScript(url,success){var script=document.createElement('script');script.src=url;var head=document.getElementsByTagName('head')[0],done=false;script.onload=script.onreadystatechange=function(){if(!done&&(!this.readyState||this.readyState=='loaded'||this.readyState=='complete')){done=true;success();script.onload=script.onreadystatechange=null;head.removeChild(script)}};head.appendChild(script)}getScript('http://cdn.jsdelivr.net/ramda/latest/ramda.min.js',function(){if(typeof ramda=='undefined'){msg='Sorry, but Ramda wasn\'t able to load'}else{msg='This page is now Ramda-fied with v'+ramda.version}return showMsg()});function showMsg(){el.innerHTML=msg;b.appendChild(el);window.setTimeout(function(){if(typeof jQuery=='undefined'){b.removeChild(el)}else{jQuery(el).fadeOut('slow',function(){jQuery(this).remove()})}},2500)}})();

Please review the API documentation.

• Introducing Ramda by Buzz de Cafe
• Why Ramda? by Scott Sauyet
• Favoring Curry by Scott Sauyet

Ok, so we like sheep. That's all. It's a short name, not already taken. It could as easily have been eweda, but then we would be forced to say eweda lamb!, and no one wants that. For non-English speakers, lambs are baby sheep, ewes are female sheep, and rams are male sheep. So perhaps ramda is a grown-up lambda... but probably not.

The functions included should automatically allow for partial application without an explicit call to lPartial. Many of these operate on lists. A single list parameter should probably come last, which might conflict with the design of other libraries that have strong functional components (I'm looking at you Underscore!)

The idea is that, if foldl has this signature:

var foldl = function(fn, accum, arr) { /* ... */}

and we have this simple function:

var add = function(a, b) {return a + b;};

then, instead of having to manually call lPartial like this:

var sum = lPartial(foldl, add, 0);
var total = sum([1, 2, 3, 4]);

with ramda, we can just do this:

var sum = foldl(add, 0);
var total = sum([1, 2, 3, 4]);

Console:

To run the test suite from the console, you need to have mocha installed:

npm install -g mocha

Then from the root of the project, you can just call

mocha

Alternately, if you've installed the dependencies, via:

npm install
npm install -g grunt-cli

then you can run the tests (and get more detailed output) via our grunt task:

grunt test

Browser:

To run the test suite in the browser, you can simply open test/index.html.

Alternatively, you can use testem to test across different browsers (or even headlessly), with livereloading of tests too. Install testem (npm install -g testem) and run testem. Open the link provided in your browser and you will see the results in your terminal.

If you have PhantomJS installed, you can run testem -l phantomjs to run the tests completely headlessly.

The eweda library was written by the developers of this library, with similar goals. But that one strove more for implementation elegance than for practical capabilities. Ramda is all about giving users real-world tools. Eweda can be seen more as an academic exercise, mostly proving out what does and doesn't work, and doing so as elegantly as possible.

Thanks to J. C. Phillipps for the Ramda logo. Ramda logo artwork © 2014 J. C. Phillipps. Licensed Creative Commons CC BY-NC-SA 3.0.