Currying

We already mentioned currying back in the Arrow functions section of Chapter 1, Becoming Functional - Several Questions, and in the One argument or many? section of Chapter 3, Starting Out with Functions - A Core Concept, but let's be more thorough here. Currying is a device that enables you to only work with single variable functions, even if you need a multiple variable one.

Note

The idea of converting a multi-variable function into a series of single-variable functions (or, more rigorously, reducing operators with several operands, to a sequence of applications of a single operand operator) had been worked on by Moses Schönfinkel, and there have been some authors who suggest, not necessarily tongue in cheek, that currying would be more correctly named Schönfinkeling!

Dealing with many parameters

The idea of currying, by itself, is simple. If you need a function with, say, three parameters, instead of writing (with arrow functions) something like the following:

const make3 = (a, b...