title: ECMA6 generators: yield promise
body: <p>As I understand it ECMA6 generators are supposed to be able to yield to a function that returns a promise, eventually returning the resolved/rejected. Making the code read more like synchronous code, and avoiding callback hell.</p>
  
  <p>I am using node.js v0.12.2 with --harmony and the following code.</p>
  
  <pre><code>var someAsyncThing = function() {
    return new Promise(function(resolve, reject) {
      resolve("I'm Resolved!");
    });
  };
  
  someAsyncThing().then(function(res) {console.log(res);});
  // Works as expected: logs I'm Resolved!
  
  function* getPromise() {
      var x = yield someAsyncThing();
      console.log("x: " + x); // Fails x undefined
  }
  
  var y = getPromise();
  console.log(y); // returns {}
  
  console.log(y.next());
  // Fails: logs { value: {}, done: false }
  </code></pre>
  
  <p>I've based the code off of the few examples I have been able to find online.  What am I doing wrong?</p>