Curry function (JavaScript)

curry.js

// Adaptation of http://chriswarbo.net/blog/2012-10-01-better_currying_in_javascript.html

/**
 * Make the inout function f curryable.
 *
 * @param {function} f
 * @returns {function}
 */
const curry = c = function(f) {
    const apply = function(args) {
        // Helper function.
        // Takes an array of arguments args, returns
        // f(args[0], args[1], ..., args[args.length - 1])
        var extra_args = args.slice(f.length);
        var result = f.apply(null, args.slice(0, f.length));
        extra_args.forEach(function(a) {
            result = result(a);
        });
        return result;
    };

    var add_args = function(old_args) {
        // Helper function.
        // Takes an array of arguments we've been given so far,
        // If they're enough for f then we run it.
        if (old_args.length >= f.length) return apply(old_args);
        // If not, we return a function to gather more.
        return function() {
            var new_args = [];
            for (var i = 0; i < arguments.length; i++)
              new_args.push(arguments[i]);
            return add_args(old_args.concat(new_args));
        };
    };

    // We kick things off by applying no arguments
    return add_args([]);
};