Functional programming in TypeScript

Inspired by PureScript, static-land, Scala.

The idea (faking higher kinded types in TypeScript) is based on Lightweight higher-kinded polymorphism

Installation

To install the stable version:

npm install --save fp-ts

TypeScript compatibility

The stable version is tested against TypeScript 3.2.4, but should run with TypeScript 2.8.0+ too

Note. If you are running < typescript@3.0.1 you have to polyfill unknown.

You can use unknown-ts as a polyfill.

Note. 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).

Ecosystem

• fp-ts-codegen - TypeScript code generation from a haskell-like syntax for ADT
• io-ts - TypeScript compatible runtime type system for IO validation
• monocle-ts - Functional optics: a (partial) porting of scala monocle to TypeScript
• newtype-ts - Implementation of newtypes in TypeScript
• logging-ts - Composable loggers for TypeScript
• fp-ts-routing - A type-safe bidirectional routing library for TypeScript
• parser-ts - String parser combinators for TypeScript
• remote-data-ts - RemoteData type (check this article)
• retry-ts - Retry combinators for monadic actions that may fail
• fp-ts-local-storage - fp-ts bindings for LocalStorage
• circuit-breaker-monad - Circuit Breaker pattern as a monad

Bindings

• fp-ts-rxjs - fp-ts bindings for RxJS
• fp-ts-fluture - fp-ts bindings for Fluture
• fp-ts-most - fp-ts bindings for @most/core

Documentation

• API Reference
• fp-ts for PureScripters / Haskellers
• Comparison with ramda

Internals

• How HKT, URI2HKT, URIS and Type work

Examples

• Free monad
• MTL-style
• OptionT monad transformer
  • ArrayOption
  • TaskOption
• EitherT monad transformer
  • EitherOption
• StateT monad transformer
  • StateIO
  • StateTaskEither
• Reader monad
• ReaderT monad transformer
  • ReaderIO
• Applicative composition
  • TaskValidation
• Type safe finite state machines with IxIO
• Moore machines
• Debugging with Trace
• fantas-eel-and-specification - Code for the Fantas, Eel, and Specification blog series on functional programming by Tom Harding

Type Classes

License

The MIT License (MIT)