Swap macro with Sweet.js

swap.js

macro swap {
	rule { $x and $y } => {
		var tmp = $x;
		$x = $y;
		$y = tmp 
	}
}

// Let's go!
var a = "a",
    b = "b";

console.log(a, b); // => a b
// And here the magic happens :3
swap a and b;

console.log(a, b); // b a