title: ECMAScript:Harmony / ES6 to JavaScript compiler
body: <p>After reading <a href="http://peter.michaux.ca/articles/javascript-is-dead-long-live-javascript">Peter's article on JavaScript</a> I noticed</p>
  
  <blockquote>
    <p>Brendan Eich stated that one the goals for Harmony is to be a better target for to-JavaScript compilers.</p>
  </blockquote>
  
  <p>There are currently two popular compilers with some vague <a href="http://wiki.ecmascript.org/doku.php?id=harmony%3aproposals">ES:Harmony</a> compliance:</p>
  
  <ul>
  <li><a href="https://github.com/google/traceur-compiler">Traceur</a></li>
  <li><a href="http://jashkenas.github.com/coffee-script/">CoffeeScript</a></li>
  </ul>
  
  <p>Although CoffeeScript has some compliance it's not designed to be an ES:Harmony compiler so it's not useful to this end.</p>
  
  <p>Tracuer seems to be sticking more rigorously to the ES:Harmony specification but I don't know whether it intends to become a full ES:Harmony compiler.</p>
  
  <p>Since the aim is to to compile ES6 down to ES3 it would also need to support ES5 features (and probably a switch whether to compile ES5 to ES3 or ES6 to ES3). </p>
  
  <ol>
  <li>Are there currently any other projects aiming to create a full ES:Harmony to ES3 compiler? </li>
  <li>Is it wise to start writing such a compiler knowing that the standard is young / unstable / in flux.</li>
  <li>Are there currently any ES5 -> ES3 compilers?</li>
  </ol>
  
  <p>I've left a question on the <a href="http://groups.google.com/group/traceur-compiler-discuss/browse_thread/thread/2974b8ed9705110c">Traceur mailing list</a>.</p>
  
  <p>The aim of such a compiler would be backwards compatibility with ES3. Not full emulation of ES5 and ES6 in ES3. </p>