Coffeescript's `do` notation as a sweet.js macro

gistfile1.js

macro $do {
    case ($($x = $y) (,) ...) $body => {
        (function ($x (,) ...) $body)($y (,) ...)
    }
    case $name ($($x = $y) (,) ...) $body => {
        (function $name ($x (,) ...) $body)($y (,) ...)
    }
}

$do (a = 1, b = 2) {
  return a + b;
}

/* result:
(function (a$15, b$16) {
    return a$15 + b$16;
}(1, 2));
*/

console.log($do fib(n=7) {
    if (n > 1) return fib(n - 1) + fib(n - 2);
    return 1;
});