Partial application

partial.js

function add(a, b, c) {
  return a + b + c;
}

function partial(fx) {
  var initial = Array.prototype.slice.call(arguments, 1);
  return function() {
    var args = Array.prototype.slice.call(arguments);
    return fx.apply(this, initial.concat(args));
  };
}

var add22 = partial(add, 2, 20);
add22(20);