Usage

const myComposedFunc = compose(
  (x) => x + 5,
  (x) => x * 2,
);

myComposedFunc(0); // => 5

Installation

CLI

npx atmx add helper compose

Manually

Copy and paste the following method into @/utils/helpers/compose.ts:

/**
* Create a function that composes multiple functions together. In a
* composition of functions, each function is given the next function
* as an argument and must call it to continue executing.
*
* @example
* const myComposedFunc = compose(
*   (x) => x + 5,
*   (x) => x * 2,
* )
*
* myComposedFunc(0) // => 5
*/
export function compose<
F1Result,
F1Args extends any[],
F1NextArgs extends any[],
LastResult,
>(
f1: (
next: (...args: F1NextArgs) => LastResult,
) => (...args: F1Args) => F1Result,
last: (...args: F1NextArgs) => LastResult,
): (...args: F1Args) => F1Result;

export function compose<
F1Result,
F1Args extends any[],
F1NextArgs extends any[],
F2Result,
F2NextArgs extends any[],
LastResult,
>(
f1: (
next: (...args: F1NextArgs) => F2Result,
) => (...args: F1Args) => F1Result,
f2: (
next: (...args: F2NextArgs) => LastResult,
) => (...args: F1NextArgs) => F2Result,
last: (...args: F2NextArgs) => LastResult,
): (...args: F1Args) => F1Result;

export function compose<
F1Result,
F1Args extends any[],
F1NextArgs extends any[],
F2NextArgs extends any[],
F2Result,
F3NextArgs extends any[],
F3Result,
LastResult,
>(
f1: (
next: (...args: F1NextArgs) => F2Result,
) => (...args: F1Args) => F1Result,
f2: (
next: (...args: F2NextArgs) => F3Result,
) => (...args: F1NextArgs) => F2Result,
f3: (
next: (...args: F3NextArgs) => LastResult,
) => (...args: F2NextArgs) => F3Result,
last: (...args: F3NextArgs) => LastResult,
): (...args: F1Args) => F1Result;

export function compose<
F1Result,
F1Args extends any[],
F1NextArgs extends any[],
F2NextArgs extends any[],
F2Result,
F3NextArgs extends any[],
F3Result,
F4NextArgs extends any[],
F4Result,
LastResult,
>(
f1: (
next: (...args: F1NextArgs) => F2Result,
) => (...args: F1Args) => F1Result,
f2: (
next: (...args: F2NextArgs) => F3Result,
) => (...args: F1NextArgs) => F2Result,
f3: (
next: (...args: F3NextArgs) => F4Result,
) => (...args: F2NextArgs) => F3Result,
f4: (
next: (...args: F4NextArgs) => LastResult,
) => (...args: F3NextArgs) => F4Result,
last: (...args: F4NextArgs) => LastResult,
): (...args: F1Args) => F1Result;

export function compose<
F1Result,
F1Args extends any[],
F1NextArgs extends any[],
F2NextArgs extends any[],
F2Result,
F3NextArgs extends any[],
F3Result,
F4NextArgs extends any[],
F4Result,
F5NextArgs extends any[],
F5Result,
LastResult,
>(
f1: (
next: (...args: F1NextArgs) => F2Result,
) => (...args: F1Args) => F1Result,
f2: (
next: (...args: F2NextArgs) => F3Result,
) => (...args: F1NextArgs) => F2Result,
f3: (
next: (...args: F3NextArgs) => F4Result,
) => (...args: F2NextArgs) => F3Result,
f4: (
next: (...args: F4NextArgs) => F5Result,
) => (...args: F3NextArgs) => F4Result,
f5: (
next: (...args: F5NextArgs) => LastResult,
) => (...args: F4NextArgs) => F5Result,
last: (...args: F5NextArgs) => LastResult,
): (...args: F1Args) => F1Result;

export function compose<
F1Result,
F1Args extends any[],
F1NextArgs extends any[],
F2NextArgs extends any[],
F2Result,
F3NextArgs extends any[],
F3Result,
F4NextArgs extends any[],
F4Result,
F5NextArgs extends any[],
F5Result,
F6NextArgs extends any[],
F6Result,
LastResult,
>(
f1: (
next: (...args: F1NextArgs) => F2Result,
) => (...args: F1Args) => F1Result,
f2: (
next: (...args: F2NextArgs) => F3Result,
) => (...args: F1NextArgs) => F2Result,
f3: (
next: (...args: F3NextArgs) => F4Result,
) => (...args: F2NextArgs) => F3Result,
f4: (
next: (...args: F4NextArgs) => F5Result,
) => (...args: F3NextArgs) => F4Result,
f5: (
next: (...args: F5NextArgs) => F6Result,
) => (...args: F4NextArgs) => F5Result,
f6: (
next: (...args: F6NextArgs) => LastResult,
) => (...args: F5NextArgs) => F6Result,
last: (...args: F6NextArgs) => LastResult,
): (...args: F1Args) => F1Result;

export function compose<
F1Result,
F1Args extends any[],
F1NextArgs extends any[],
F2NextArgs extends any[],
F2Result,
F3NextArgs extends any[],
F3Result,
F4NextArgs extends any[],
F4Result,
F5NextArgs extends any[],
F5Result,
F6NextArgs extends any[],
F6Result,
F7NextArgs extends any[],
F7Result,
LastResult,
>(
f1: (
next: (...args: F1NextArgs) => F2Result,
) => (...args: F1Args) => F1Result,
f2: (
next: (...args: F2NextArgs) => F3Result,
) => (...args: F1NextArgs) => F2Result,
f3: (
next: (...args: F3NextArgs) => F4Result,
) => (...args: F2NextArgs) => F3Result,
f4: (
next: (...args: F4NextArgs) => F5Result,
) => (...args: F3NextArgs) => F4Result,
f5: (
next: (...args: F5NextArgs) => F6Result,
) => (...args: F4NextArgs) => F5Result,
f6: (
next: (...args: F6NextArgs) => F7Result,
) => (...args: F5NextArgs) => F6Result,
f7: (
next: (...args: F7NextArgs) => LastResult,
) => (...args: F6NextArgs) => F7Result,
last: (...args: F7NextArgs) => LastResult,
): (...args: F1Args) => F1Result;

export function compose<
F1Result,
F1Args extends any[],
F1NextArgs extends any[],
F2NextArgs extends any[],
F2Result,
F3NextArgs extends any[],
F3Result,
F4NextArgs extends any[],
F4Result,
F5NextArgs extends any[],
F5Result,
F6NextArgs extends any[],
F6Result,
F7NextArgs extends any[],
F7Result,
F8NextArgs extends any[],
F8Result,
LastResult,
>(
f1: (
next: (...args: F1NextArgs) => F2Result,
) => (...args: F1Args) => F1Result,
f2: (
next: (...args: F2NextArgs) => F3Result,
) => (...args: F1NextArgs) => F2Result,
f3: (
next: (...args: F3NextArgs) => F4Result,
) => (...args: F2NextArgs) => F3Result,
f4: (
next: (...args: F4NextArgs) => F5Result,
) => (...args: F3NextArgs) => F4Result,
f5: (
next: (...args: F5NextArgs) => F6Result,
) => (...args: F4NextArgs) => F5Result,
f6: (
next: (...args: F6NextArgs) => F7Result,
) => (...args: F5NextArgs) => F6Result,
f7: (
next: (...args: F7NextArgs) => LastResult,
) => (...args: F6NextArgs) => F7Result,
f8: (
next: (...args: F8NextArgs) => LastResult,
) => (...args: F7NextArgs) => F8Result,
last: (...args: F8NextArgs) => LastResult,
): (...args: F1Args) => F1Result;

export function compose<
F1Result,
F1Args extends any[],
F1NextArgs extends any[],
F2NextArgs extends any[],
F2Result,
F3NextArgs extends any[],
F3Result,
F4NextArgs extends any[],
F4Result,
F5NextArgs extends any[],
F5Result,
F6NextArgs extends any[],
F6Result,
F7NextArgs extends any[],
F7Result,
F8NextArgs extends any[],
F8Result,
F9NextArgs extends any[],
F9Result,
LastResult,
>(
f1: (
next: (...args: F1NextArgs) => F2Result,
) => (...args: F1Args) => F1Result,
f2: (
next: (...args: F2NextArgs) => F3Result,
) => (...args: F1NextArgs) => F2Result,
f3: (
next: (...args: F3NextArgs) => F4Result,
) => (...args: F2NextArgs) => F3Result,
f4: (
next: (...args: F4NextArgs) => F5Result,
) => (...args: F3NextArgs) => F4Result,
f5: (
next: (...args: F5NextArgs) => F6Result,
) => (...args: F4NextArgs) => F5Result,
f6: (
next: (...args: F6NextArgs) => F7Result,
) => (...args: F5NextArgs) => F6Result,
f7: (
next: (...args: F7NextArgs) => LastResult,
) => (...args: F6NextArgs) => F7Result,
f8: (
next: (...args: F8NextArgs) => LastResult,
) => (...args: F7NextArgs) => F8Result,
f9: (
next: (...args: F9NextArgs) => LastResult,
) => (...args: F8NextArgs) => F9Result,
last: (...args: F9NextArgs) => LastResult,
): (...args: F1Args) => F1Result;

export function compose(...funcs: ((...args: any[]) => any)[]) {
return funcs.reverse().reduce((acc, fn) => fn(acc));
}