Function Currying in JavaScript

Introduction

In this lab, we will explore the concept of function currying and uncurrying in JavaScript. Function currying is a technique that allows us to transform a function that takes multiple arguments into a sequence of functions that each take a single argument. On the other hand, function uncurrying is the process of transforming a sequence of functions that each take a single argument into a function that takes multiple arguments. Through this lab, we will learn how to implement both these techniques in JavaScript.

Uncurry a Function

To uncurry a function up to a specified depth, use the uncurry function.

const uncurry =
  (fn, n = 1) =>
  (...args) => {
    const next = (acc) => (args) => args.reduce((x, y) => x(y), acc);
    if (n > args.length) throw new RangeError("Arguments too few!");
    return next(fn)(args.slice(0, n));
  };

To use the uncurry function, pass the function you want to uncurry and the depth up to which you want to uncurry it as arguments. The function will return a variadic function that you can call with the arguments you want to pass.

If you don't specify the depth, the function will uncurry up to depth 1.

const add = (x) => (y) => (z) => x + y + z;
const uncurriedAdd = uncurry(add, 3);
uncurriedAdd(1, 2, 3); // 6

If the number of arguments you pass is less than the specified depth, the function will throw a RangeError.

Summary

Congratulations! You have completed the Uncurry Function lab. You can practice more labs in LabEx to improve your skills.