Auto-currying for the masses

auto_curry.js

Function.prototype._curry = function (f=this) {
  return (...args) => args.length < f.length
    ? f._curry(args.reduce((g, arg) => g.bind(null, arg), f)) 
    : f.apply(null, args);
};

example.js

var adder = function(a,b,c) {
  return a + b + c;
};

var add = adder._curry();
var add3 = add(1)(2)

console.log(add(1)(2)(3)) //=> 6
console.log(add(4,5)(6))  //=> 15
console.log(add3(5))      //=> 8