Currying a function in js

curry.js

"use strict";
/* global require, console, module */

var arr = function (x) {
  return Array.prototype.slice.call(x);
};

var args = function (str) {
  return str.substring(str.indexOf("(")+1, str.indexOf(")")).split(",");
};

var curry = function (fun, total, args) {
  if (!args) args = [];
  
  var base = function () {
    var curr_args = arr(arguments);
    return fun.apply(this, args.concat(curr_args));
  };

  var indve = function () {
    var prev_args = args.concat(arr(arguments));
    return curry(fun, total-1, prev_args);
  };

  indve.toString = base.toString = function () {
    return fun.toString() + " (" + args.join(",") + ", ...)";
  };

  return (total === 1) ? base : indve;
};

Function.prototype.curry = function () {
  var first_line = this.toString().split("\n")[0];
  return curry(this, args(first_line).length, []);
};

if (require.main === module) {
  var echo = function () {
    console.log('lomo', arr(arguments));
  };

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

  var cadd = curry(add,3);
  console.log(cadd(1)(2)(1));
  var cecho = curry(echo, 3);
  console.log(cecho(1)(2)(1));
  var woah_add = add.curry();
  console.log(woah_add(1)(2));
}