prelude

a base library for functional programming in deno

Roadmap

⚠️ WATCH OUT!

semver won’t be enforced until v1.0.0
partial application and other tuple related functions won’t be available until deno supports TypeScript 4.0

Goals

provide interfaces corresponding to static-land spec type classes and factory functions for implementing its instances
provide a good replacement for libraries like fp-ts, ramda, hkts and lodash
provide interfaces for additional purescript based type classes
provide some basic (primitives, Maybe, Either, etc…) instances for existing type classes
support and idioms for deno comes first, but browser and node should be compatible

Non-Goals

break compatibility with static-land
provide every type class and instance corresponding to haskell/purescript
requiring abstractions with higher runtime cost than handwritten functional code

Documentation

Is currently a work in progress and not a priority until instances for most primitive types are implemented.

Known limitations

every kind is limited to a single parameter (but kinds can yield kinds)
testing kind applications is weird
a useless expression is required to check type class instances:

(():
  & Monoid<Ap<ArrayKind, unknown>>
  & Setoid<Ap<ArrayKind, unknown>>
  & Semigroup<Ap<ArrayKind, unknown>>
  & Group<Ap<ArrayKind, unknown>>
  & Functor<ArrayKind>
  & Foldable<ArrayKind>
  & Filterable<ArrayKind>
  & Apply<ArrayKind>
  & Applicative<ArrayKind>
  & Chain<ArrayKind>
  & Monad<ArrayKind> => ({
  equals,
  empty,
  concat,
  map,
  reduce,
  filter,
  ap,
  of,
  chain,
  join,
  invert,
}));

encoding higher kinded types in typescript without declaration merging
inspired by hkts, fp-ts and purescript

For Developers

If you want to contribute to prelude:

clone this repository
make sure you have deno installed in your path
install the pre-commit running:
- on linux/unix-likes: ./scripts/hook from the repository root directory
- on windows with cmder: sh scripts/hook from the repository root directory
run scripts from the repository root directory

Thanks!