Example of Static Extension in Haxe , see also http://haxe.org/manual/lf-static-extension.html

Main.hx

using Main.StringExtender;

class Main {
  static function main() {
    trace("hallo".makeUp());
  }
}

class StringExtender {
  static function makeUp(s:String) {
    return s.toUpperCase();
  }
}

compiles to:

(function () { "use strict";
var Main = function() { };
Main.main = function() {
        console.log(StringExtender.makeUp("hallo"));
};
var StringExtender = function() { };
StringExtender.makeUp = function(s) {
        return s.toUpperCase();
};
Main.main();
})();