@k88/pipe-compose

ES6-like pipe, compose, p-pipe, and p-compose in JavaScript, inspired by this Medium post.

What is it?

This library exports 6 functions: pipe, compose, cPipe, cCompose, pPipe, and pCompose.

Pipe and Compose

To paraphrase the Medium post, image you want to pipe the output of n-functions together. You'll end up with something like:

reverse(get3Chars(uppercase('the-argument')));
// EHT

In this example, you first uppercase to get THE-ARGUMENT, then you get3Chars and have THE and finally you reverse it to get EHT.

With pipe you can accomplish the same thing using:

pipe('the-argument', uppercase, get3Chars, reverse);

It helps to read this similar to bash's pipe |:

echo 'the-argument' | uppercase | get3Chars | reverse;

compose is the reverse of pipe. For example these two would return the same result.

pipe('the-argument', uppercase, get3Chars, reverse);
compose('the-argument', reverse, get3Chars, uppercase);

cPipe and cCompose

These are composable versions of pipe and compose, i.e.:

const textModifier = cPipe(uppercase, get3Chars, reverse);

textModifier('the-argument');
// EHT

textModifier('another-argument');
// ONA

pPipe and pCompose

There are also composable promise version of the pipe and compose.

const calc = pPipe(add1, multiply2, divide3);
await calc(2);
// 2

In this example, we are creating a calculation function that takes in an number, and performs basic math operation on it. In this case, we are passing 2 and first adding 1 to it (giving us 3), then multiplying by 2 (giving us 6) and finally dividing by 3 (giving us back 2).

As before, pCompose would work in the reverse:

const calc = pCompose(add1, multiply2, divide3);
await calc(6);
// 5

How to use it

Installing NPM package

Install from npm:

npm install @k88/pipe-compose

and use it:

import { pipe, compose } from '@k88/pipe-compose';

Get the source code

All of these auxiliary functions are one-liner, so you can also just copy/paste them into your application:

const pipe = (x, ...fns) => fns.reduce((v, f) => f(v), x);
const compose = (x, ...fns) => fns.reduceRight((v, f) => f(v), x);

const cPipe = (...fns) => (x) => => fns.reduce((v, f) => f(v), x);
const cCompose = (...fns) => (x) => fns.reduceRight((v, f) => f(v), x);

const pPipe = (...fns) => async (x) => fns.reduce(async (v, f) => f(await v), x);
const pCompose = (...fns) => async (x) => fns.reduceRight(async (v, f) => f(await v), x);