compose-function

What is compose-function?

The compose-function npm package provides utility functions for function composition, allowing you to combine multiple functions into a single function. This is particularly useful in functional programming paradigms where you want to create complex operations by combining simpler ones.

What are compose-function's main functionalities?

compose

The `compose` function allows you to combine multiple functions into a single function. In this example, `addThenMultiply` first adds 1 to the input and then multiplies the result by 2.

const compose = require('compose-function');

const add = x => x + 1;
const multiply = x => x * 2;

const addThenMultiply = compose(multiply, add);
console.log(addThenMultiply(5)); // Output: 12

pipe

The `pipe` function is similar to `compose` but applies functions from left to right. In this example, `multiplyThenAdd` first multiplies the input by 2 and then adds 1.

const { pipe } = require('compose-function');

const add = x => x + 1;
const multiply = x => x * 2;

const multiplyThenAdd = pipe(add, multiply);
console.log(multiplyThenAdd(5)); // Output: 11

Other packages similar to compose-function

lodash

Lodash is a popular utility library that provides a wide range of functions for common programming tasks, including function composition. The `_.flow` and `_.flowRight` methods in Lodash offer similar functionality to `compose` and `pipe` in compose-function.

ramda

Ramda is a functional programming library for JavaScript that emphasizes immutability and side-effect-free functions. It provides `R.compose` and `R.pipe` functions, which are similar to the compose-function package but come with additional functional programming utilities.

redux

Redux is a state management library for JavaScript applications. It includes a `compose` function that is often used to apply multiple middleware functions in a Redux store. While its primary focus is state management, its `compose` function can be used similarly to the compose-function package.

README

Compose-Function

Installation | Usage | Related | License


_{logo by Justin Mezzell}

Compose a new function from smaller functions `f(g(x))`

Installation

npm install compose-function

Usage

Basic usage

import compose from 'compose-function';

const composition = compose(sqr, add2); // sqr(add2(x))

composition(2) // => 16

compose(sqr, inc)(2); // => 9
compose(inc, sqr)(2); // => 5

with curry

import compose from 'compose-function';
const { curry, _ } = require('curry-this')({Symbol:() => 'CURRY'});


const add = (x, y) => x + y;

// add(6, sqr(add(2, x)))
compose(
  add::curry(6),
  sqr,
  add::curry(2),
);

// map(filter(list, even), sqr)
compose(
  map::curry(_, sqr),
  filter::curry(_, even),
)([1,2,3,4,5,6,7,8]) // => [4, 16, 36, 64]

:: huh?

If you’re wondering what the :: thing means, you’d better read this excellent overview by @jussi-kalliokoski or have a look at the function bind syntax proposal. Or checkout the curry-this docs.

Related

• curry-this

License

MIT © Christoph Hermann