Sweet.js上でマクロを定義する動かないマクロ

macro.js

macro fun {
  rule {
    $name($param (,) ...) {
      $body ...
    }
  } => {
    macro $name {
      rule { ($param (,) ...) } => {
        $body ...
      }
    }
  }
}


fun swap(a, b) {
  var tmp = $a;
  $a = $b;
  $b = tmp;
}

/*
macro swap {
  rule { ($a, $b) } => {
    var tmp = $a;
    $a = $b;
    $b = tmp
  }
}*/

var tmp = 10;
var b = 20;

swap(tmp, b);