title: How to use Promise.all() with Typescript
body: <p>Here is what I want to do:</p>
  
  <pre><code>Promise.all([aurelia.start(), entityManagerProvider.initialize()])
      .then((results:Array&lt;any&gt;) =&gt; {
          let aurelia: any = results[0];
          aurelia.setRoot();
      });
  </code></pre>
  
  <p><code>aurelia.start()</code> returns an Aurelia type, while <code>initialize()</code> returns void.</p>
  
  <p>The compiler gives an error message that the type cannot be inferred from the usage.</p>
  
  <p>What I am trying to achieve is to get them to run at the same time, as they are both very long processes, then run <code>Aurelia.setRoot();</code>  </p>