title: Typescript and React setting initial state with empty typed array
body: <p>Say I have the following snippet:</p>
  
  <pre><code>interface State {
    alarms: Alarm[];
  }
  export default class Alarms extends React.Component&lt;{}, State&gt; {
    state = {
      alarms: []
    };
  </code></pre>
  
  <p>Since I am trying to set <code>alarms: []</code> Typescript doesn't like it, as <code>[] != Alarm[]</code>. I found that I can use <code>alarms: new Array&lt;Alarm&gt;()</code> which initializes an empty typed array, however I don't really like this syntax - is there an easier/better approach?</p>