hkts

Higher kinded types for Deno. As an avid user of fp-ts I wanted to have a similarly full featured environment in Deno. Unfortunately, the fp-ts port to Deno is clunky to use with other functional libraries like @nll/datum, io-ts, and monocle-ts. While I could have ported fp-ts directly, I’ve come to like the exploratory work done by pelotom in the original hkts. Thus, I’ve decided to port the functionality of fp-ts, io-ts, and monocle-ts to Deno using the HKT substitution developed by pelotom.

This library is primarily an exercise, but I intend to maintain 100% test coverage. Instead of breaking out the clones of io-ts, monocle-ts, and datum into other Deno modules they will all be landed here. There will be no barrel exports as importing in Deno is much cleaner without them. Contributions are welcome.

Installation

This library is meant to be used with Deno, thus it follows the Deno imports syntax.

import * as O from "https://deno.land/x/hkts/option.ts";
import { pipe } from "https://deno.land/x/hkts/pipe.ts";

const result = pipe(
    O.some(1),
    O.map(n => n + 1),
    O.chain(n => n % 2 === 0 ? O.none, O.some(n))
);
// result = O.none.