hyper-async

Async is a tiny FP library for javascript. It provides a small, composable abstraction over async effects with predictable error handling and strict composition semantics.

install

npm install hyper-async

Usage

Composition and errors

• map(fn): fn must be a function. Sync throws inside fn are caught and become a rejected Async.
• chain(fn): fn must return an Async. If it returns anything else, the chain rejects with a TypeError.
• bimap(rejFn, resFn): both args must be functions.
• bichain(rejFn, resFn): both args must return Async.
• fold(rejFn, resFn): both args must return Async.
• fromPromise(f): f must be a function; sync throws reject the Async.

Errors never escape; they surface as a rejected Async (and thus a rejected .toPromise()).

import Async from "hyper-async";

const prop = (k) => (o) => o[k];

async function main() {
  const x = await Async.of(1)
    .chain((n) => Async.fromPromise(fetch)(`https://example.test/posts/${n}`))
    .chain((res) => Async.fromPromise(res.json.bind(res))())
    .map(prop("title"))
    .toPromise();
  console.log(x);
}

main();