fp-async-utils

A type-safe library that exposes a handful of helpful FP-inspired utilities to work with asynchronous code. No dependencies.

Installation

npm i fp-async-utils

Usage

pipe

Apply a series of asynchronous OR synchronous functions to an input. Always returns a Promise.

const addTwo = async (value: number) => value + 2;
const addTwoSync = (value: number) => value + 2;
const result = await pipe(1, addTwo, addTwoSync);
console.log(result); // 5

flow

Compose a function from a series of other functions applied left-to-right

const addTwo = async (value: number) => value + 2;
const addTwoSync = (value: number) => value + 2;
const addFour = flow(addTwo, addTwoSync);
const result = await addFour(1);
console.log(result); // 5

ado

Inspired by applicative-do notiation. Takes an object where each key value is a promise and returns an object with the same keys where each value is the resolution of the promise.

const promiseObj = {
  a: Promise.resolve(1),
  b: Promise.resolve(2),
};
const resolvedObj = await ado(promiseObj);
console.log(resolvedObj.a); // 1

map

Apply a series of asynchronous OR synchronous functions to every item in an array. Always returns a Promise.

const arr = [1, 2, 3];
const addTwo = async (value: number) => value + 2;
const result = await pipe(arr, map(addTwo));
console.log(result); // [3, 4, 5]

filter

Apply a asynchronous OR synchronous predicate to filter out items in an array. Always returns a Promise.

const arr = [1, 2, 3];
const isEven = async (n: number) => n % 2 == 0;
const result = await pipe(arr, filter(isEven));
console.log(result); // [2]

setIn

Sets a value to an object's property

const obj = { a: 1, b: 1 };
const result = await pipe(2, setIn(obj, "b"));
console.log(result); // { a: 1, b: 2 }