Javascript partial application

partial.js

function swap(f)
{
	return function(a, b)
	{
		return f(b, a);
	};
}

function ArgPos(i)
{
	this.argInd = i;
}

function _(){}
$1 = new ArgPos(0);
$2 = new ArgPos(1);
$3 = new ArgPos(2);
$4 = new ArgPos(3);
$5 = new ArgPos(4);
$6 = new ArgPos(5);
$7 = new ArgPos(6);
$8 = new ArgPos(7);
$9 = new ArgPos(8);


//-----PARTIAL APPLICATION AND ARG REARANGEMENT: 

function $$()
{
	if(arguments.length < 1)
		return _;
	else if(arguments.length == 3 && arguments[1] == $2 && arguments[2] == $1)
		return swap(arguments[0]);
		
	var f = arguments[0];
	var callArgs = Array.prototype.slice.call(arguments, 1);
	
	return function()
	{
		var index = 0;
		for(var i = 0; i < callArgs.length; ++i)
		{
			if(callArgs[i] == _)
			{
				callArgs[i] = arguments[index];
				index++;
			}
			else if(callArgs[i] instanceof ArgPos)
			{
				callArgs[i] = arguments[callArgs[i].argInd];
			}
		}
		return f.apply(null, callArgs);
	};
}