There are already several excellent libraries with a functional flavor. Typically, they are meant to be general-purpose toolkits, suitable for working in multiple paradigms. Ramda has a more focused goal. We wanted a library designed specifically for a functional programming style, one that makes it easy to create functional pipelines, one that never mutates user data.
The primary distinguishing features of Ramda are:
Ramda emphasizes a purer functional style. Immutability and side-effect free functions are at the heart of its design philosophy. This can help you get the job done with simple, elegant code.
Ramda functions are automatically curried. This allows you to easily build up new functions from old ones simply by not supplying the final parameters.
The parameters to Ramda functions are arranged to make it convenient for currying. The data to be operated on is generally supplied last.
The last two points together make it very easy to build functions as sequences of simpler functions, each of which transforms the data and passes it along to the next. Ramda is designed to support this style of coding.
Also see Why Ramda?, Why Curry Helps and Hey Underscore, You're Doing It Wrong!.
Functional programming is in good part about immutable objects and side-effect free functions. While Ramda does not enforce this, it enables such style to be as frictionless as possible.
We aim for an implementation both clean and elegant, but the API is king. We sacrifice a great deal of implementation elegance for even a slightly cleaner API.
Last but not least, Ramda strives for performance. A reliable and quick implementation wins over any notions of functional purity.
To use with node:
$ npm install ramda
Then in the console:
var R = require('ramda');
To use directly in the browser:
or the minified version:
or from a CDN, either cdnjs:
or one of the below links from jsDelivr:
<script src="//cdn.jsdelivr.net/ramda/0.19.1/ramda.min.js"></script> <script src="//cdn.jsdelivr.net/ramda/0.19/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
R on the browser's global scope.
Or you can inject ramda into virtually any unsuspecting website using the bookmarklet.
- on Unix-based platforms,
npm run buildupdates dist/ramda.js and dist/ramda.min.js
- on Windows, write the output of
scripts/build --completeto a temporary file, then rename the temporary file dist/ramda.js.
It is possible to build Ramda with a subset of the functionality to reduce its file size. Ramda's build system supports this with command line flags. For example if you're using
R.filter you can create a partial build with:
./scripts/build -- src/compose.js src/reduce.js src/filter.js > dist/ramda.custom.js
This requires having Node/io.js installed.
Please review the API documentation.
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.
Running The Test Suite
To run the test suite from the console, you need to have
npm install -g mocha
Then from the root of the project, you can just call
Alternately, if you've installed the dependencies, via:
then you can run the tests (and get detailed output) by running:
To run the test suite in the browser, you can simply open
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.
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.