Simple function currying.

curry.js

let curry = fn => {
	let total = fn.length;
	let len = 0;
	let argarr = [];
	let recur = (...args) => {
		len += args.length;
		argarr = argarr.concat(args);
		return len >= total ? fn(...argarr) : recur;
	}
	return recur;
}