Functional programming in TypeScript

fp-ts is a library for typed functional programmingin TypeScript.

fp-ts aims to allow developers to use popular patterns and abstractionsthat are available in most functional languages. For this, it includes the most popular data types, type classes and abstractions such as Option, Either, IO, Task, Functor, Applicative, Monad to empower users to write pure FP apps and libraries built atop higher order abstractions.

A distinctive feature of fp-ts with respect to other functional libraries is its implementation of Higher Kinded Types, which TypeScript doesn't support natively.

Haskell

PureScript

Scala

To install the stable version:

Make sure to always have a single version of fp-ts installed in your project. Multiple versions are known to cause tsc to hang during compilation. You can check the versions currently installed using npm ls fp-ts (make sure there's a single version and all the others are marked as deduped ).

Strictness– This library is conceived, tested and is supposed to be consumed by TypeScript with the strict flag turned on.

(*) If you are running < typescript@3.0.1 you have to polyfill the unknown type. You can use unknown-ts as a polyfill.

Disclaimer. Teaching functional programming is out of scope of this project, so the documentation assumes you already know what FP is.

Docs

Learning Resources

Ecosystem

API Reference

version 2.x (current)

version 1.x

If you need help with fp-ts check out:

this Discord server

the #fp-ts channel on FP slack.

Code conventions

The MIT License (MIT)