Playing around with macro's using sweet.js. Here is an attempt at sweetening privacy with private maps.

gistfile1.js

/*
  Sweet.js macros for privacy sugar. 
  Below could be rewritten using es6 weakmaps.
*/
macro privacy {
    rule {} => {
        var id = ++privates.id
        var privMap = {}
        this.__id = id
        privates[id] = privMap
    }
}

macro class {
    rule {
        $className {
            constructor $cparams $cbody
            $($mname $mparams $mbody) ...
        }
    } => {
        function $className $cparams $cbody
            $($className.prototype.$mname
        
        = function $mname $mparams $mbody; ) ...
    }
}

macro @ {
    rule { $x = $y } => {
        privates[this.__id].$x = $y
    }
    rule { $x } => {
        privates[this.__id].$x
    }
}

var privates = { id: 0 };

class BazBar {
    constructor() {
        privacy;
        @color = "blue";
        @size = 200;
    }
	
    baz() {
        console.log(@color);
        console.log(@size * 10);
    }
}

var bar = new BazBar();
bar.baz();

The id set on the object should be exposed as a getter.