compose-typed

A very small library for a set of compose functions that are flow-typed

API

compose2

import { compose2 } from 'compose-typed'

const addTen = (x: number) => x + 10;
const addFive = (x: number) => x + 5;

const addFifteen = compose2(addFive, addTen);

Composes two functions together. Generically typed using flow.

Parameters

Accepts two functions, where the output of the first function is the input of the second.

  (
    func1: (i: X) => Y,
    func2: (i: Y) => Z,
  )

• fun1 ((i: InputType): IntermediateType)
• fun2 ((i: IntermediateType): OutputType)

Output

Returns a function that takes the type of the first argument's input, and return the type of the second's output.

compose(
  (i: X) => Y,
  (i: Y) => Z,
): X => Z

compose(n)

This api also exposes compose3 and compose4, with identical functionality but accepting of more arguments to pass through.

import { compose3, compose4 } from 'compose-typed'

const addFive = x => x + 5;
const addTen = x => x + 10;
const addTwenty = x => x + 20;

const addThirtyFive = compose3(addFive, addTen, addTwenty);

const speakString = x => `The Number is: ${x}`;
const convertToString = x => x.toString();

const addThirtyFiveAndSpeak = compose4(
  addThirtyFive,
  convertToString,
  speakString,
  console.log,
);

addThirtyFiveAndSpeak(5); // 'The Number is: 40'