compose

/**
 * Compose functions from right to left.
 *
 * compose(f, g, h)(x) => f(g(h(x)))
 *
 * If no functions are provided, returns identity function.
 *
 * @param {...Function} functions
 * @returns {(input: unknown) => unknown}
 */
export default function compose(...functions) {
	if (functions.length === 0) {
		return (input) => input;
	}

	return (input) =>
		functions.reduceRight((accumulator, fn) => fn(accumulator), input);
}

/**
Example:

const add1 = (num) => num + 1;
const double = (num) => num * 2;
const subtract10 = (num) => num - 10;

const composedFn = compose(subtract10, double, add1);
composedFn(3); // -2

const identity = compose();
identity(7); // 7
*/