Awesome functional programming in JavaScript

A curated list of awesome functional programming in JavaScript. Origin here, suggestions and PRs are welcome.

Table of Contents


  • Ramda – A practical functional library for JavaScript that is designed specifically for a functional programming style. A style that makes it easy to create functional pipelines and never mutates user data.
  • Folktale – Folktale is a suite of libraries for generic functional programming that allows you to write elegant modular applications with fewer bugs and more reuse.
  • lodash/fp – An instance of Lodash with its methods wrapped to produce immutable, auto-curried, iteratee-first, data-last methods.
  • functional.js – A lightweight functional JavaScript library that facilitates currying and point-free / tacit programming.
  • 101 – A modern and modular JavaScript utility library made to work well with vanilla JavaScript methods.
  • fnuc – A functional library for CoffeeScript (and JavaScript) to facilitate functional composition and higher order functions.
  • barely-functional – A tiny (2.7kb) functional programming library using native ES5/6 operations.
  • – A functionally oriented utility library somewhat based off of Haskell's Prelude module.
  • – A collection of functions to facilitate writing JavaScript with functions as first-class values, designed to complement libraries like Underscore, not compete with them.
  • 1-liners – Functional tools that couldn’t be simpler. A dead simple functional utility belt, hand-crafted with love and attention.
  • fn-curry – A simple function to curry a function.
  • curry – Curry your functions using function bind syntax.
  • compose-function – Compose a new function from smaller functions.
  • functionize – A collection of functions which aid in making non-functional libraries functional.
  • lambdajs – The full ECMAScript API done a functional way.
  • fp-dom – Making the DOM functional.
  • trifl – A functional user interface library with unidirectional dataflow and a virtual dom.
  • funcy – An experiment in adding functional pattern matching to JavaScript. Experimental :triangular_flag_on_post:
  • date-fp – A functional utility library for working with JavaScript dates. All functions in date-fp are pure, autocurried and will not mutate the date objects they are applied to.
  • _part_ – A micro library that encourages functional programming by making native methods available as partially applied functions.
  • claire – A property-based testing library for clearly specifying code invariants and behaviour.

Data Structures

Write performant functional code by using the right data structures for the task.
  • Immutable.js – Immutable persistent data collections.
  • Mori – ClojureScript’s persistent data structures and supporting API from the comfort of vanilla JavaScript.
  • immutable-sequence.js – High performance implementation of Immutable Sequence in JavaScript, based on Finger Trees.
  • Timm – Immutability helpers with fast reads and acceptable writes.
  • Lazy.js – A utility library with a lazy engine under the hood that strives to do as little work as possible while being as flexible as possible.

Algebraic Data Types

Use the laws of math instead of always reinventing your own thing. Algebraic!
  • FantasyLand – Not a library, but a specification of the Monad laws for libraries to follow.
  • daggy – Library for creating tagged constructors.
  • Sanctuary – Sanctuary makes it possible to write safe code without null checks.
  • ramda-fantasy – Fantasy-Land compatible types for easy integration with Ramda.js.
  • monet.js – A library that assists functional programming by providing a rich set of Monads and other useful functions.
  • union-type – A small JavaScript library for defining and using union types.
  • freeky – A collection of Free monads.
  • Fluture – A Future library with included control utilities, high performance and great error messages.
  • fantasy-combinators – Common combinators.
  • fantasy-birds – Port of the Haskell package Data.Aviary.Birds. Everything for your combinatory needs.


  • lenses – Composable kmett style lenses.
  • optics – Profunctor optics (Lens, Prism, iso).
  • ramda-lens – :ram: :mag_right: Lens library built on Ramda.
  • fantasy-lenses – Composable, immutable getters and setters. (Profunctor lenses WIP)
  • nanoscope – Lenses with dotty support.
  • partial.lenses – Ramda compatible partial lenses. View, insert and update optional data.

Functional Languages that Compile to JavaScript

  • ClojureScript – Compiles Clojure, a hosted Lisp with immutable persistent data structures, to JavaScript.
  • Elm – A type-safe functional programming language for declaratively creating web browser-based graphical user interfaces. Implemented in Haskell.
  • PureScript – A small strongly typed programming language that compiles to JavaScript.
  • Idris – A general purpose pure functional programming language with dependent types.
  • GHCJS – Haskell to JavaScript compiler, based on GHC.
  • ElixirScript – Compiles a subset of Elixir, a dynamic, functional language designed for building scalable and maintainable applications, to JavaScript.
  • Js_of_ocaml – Compiles OCaml bytecode to JavaScript, making it possible to run OCaml programs in the browser.
  • Scala.js – Compiles Scala to JavaScript.
  • LiveScript – LiveScript has a straightforward mapping to JavaScript and allows you to write expressive code devoid of repetitive boilerplate.





Examples and Exercises

  • FPJS-Class – Functional Programming learned through JS
  • functional-javascript-workshop – Teaching fundamental functional programming features of JavaScript
  • functional-frontend-architecture – A functional frontend framework. Based on Ramda + union-type-js + Flyd + Snabbdom
  • cube-composer – A puzzle game inspired by functional programming.
  • FP Youtube Search – YouTube search app with ReactJS, Redux, and FP concepts
  • Hardcore Functional Programming in JavaScript – Learn to apply techniques from the forefront of computer science research to solve practical problems in Javascript. Discover functional programming and see it demonstrated step-by-step with how to build an example web app using abstract interfaces like Monads, Functors, Monoids and Applicatives. (commercial)