GitHub 6219★

Compose functions

JavaScript version

// Compose functions from right to left
const compose =
(...fns) =>
(x) =>
fns.reduceRight((y, f) => f(y), x);

Examples

const lowercase = (str) => str.toLowerCase();
const capitalize = (str) => `${str.charAt(0).toUpperCase()}${str.slice(1)}`;
const reverse = (str) => str.split('').reverse().join('');

const fn = compose(reverse, capitalize, lowercase);

// We will execute `lowercase`, `capitalize` and `reverse` in order
fn('Hello World') === 'dlrow olleH';
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