auto curry in JavaScript

gistfile1.js

function toArray(args) {
  return [].slice.call(args);
}

function autocurry(fn) {
  var len = fn.length;
  var args = [];
  return function next() {
    args = args.concat(toArray(arguments));
    return (args.length >= len) ? 
      fn.apply(this, args.splice(0)) : 
      next;
  }
}

// usage

var add = autocurry(function (a, b, c, d) {
  return a + b + c + d;
});

add(1)(2)(3)(4); // 10

var one = add(1);
one(4, 5, 6); // 16


add(2)(3, 4)(5); // 14

Fixed curry function that does not store state in scope between multiple calls (also typed for up-to 2 arguments):

export function curry<A1, R>(fn: (arg1: A1) => R): (arg1: A1) => R;
export function curry<A1, A2, R>(fn: (arg1: A1, arg2: A2) => R): (arg1: A1) => (arg2: A2) => R;
export function curry<T extends (...args: any) => any>(fn: T): (...args: any[]) => any {
  return function(...firstArgs) {
    const argsLen = fn.length;
    let allArgs = [];

    return nextArgument(...firstArgs);

    function nextArgument(...args) {
      allArgs = allArgs.concat(args);
      return allArgs.length >= argsLen ? fn.apply(this, allArgs) : nextArgument;
    }
  };
}