title: TypeScript interface with spread members
body: <p>I'm bulk importing a bunch of properties with</p>
  
  <p><code>import * as actionCreators from './billingUtil2';</code></p>
  
  <p>and TypeScript is correctly identifying each export inside of <code>actionCreators</code>.  Is it possible to "spread" those members into an interface?  Ideally something like this, but valid</p>
  
  <pre><code>interface componentState {
      ...actionCreators
  }
  </code></pre>
  
  <hr>
  
  <p>My use case is, I'd like to create a React component and accurately describe the shape of the props it'll be receiving from Redux.  So ideally something along these lines</p>
  
  <pre><code>import * as actionCreators from './billingUtil2';
  
  interface State {
      name: string;
      age: number
  }
  
  interface componentState extends State {
      ...actionCreators
  }
  </code></pre>
  
  <p>and then I could tell TypeScript to expect props of the form <code>componentState</code>. 
   My redux reducers would already be returning results implementing an interface; my main goal here is to avoid manually typing out each action creator. </p>