curry_uncurry.js

const uncurry = (fn) => (...args) => args.reduce((fn, arg) => fn(arg), fn);
const curry = (fn) => {
  const collect = (args, arg) => {
    const collected = args.concat([arg]);
    return (
      collected.length >= fn.length
      ? fn.apply(null, collected)
      : collect.bind(null, collected)
    );
  };

  return collect.bind(null, []);
};