title: Typescript nullable Array
body: <p>I am testing Typescript and I ran into troubles with Array, interface and nullable variable :</p>
  
  <p>I have this interface :</p>
  
  <pre><code>interface Entity {
      life: number;
      type: EntityType;
  }
  </code></pre>
  
  <p>And I have this property :</p>
  
  <pre><code>world: Entity[];
  </code></pre>
  
  <p>I am trying to initialize with :</p>
  
  <pre><code>this.world = [
      [null, null, null, null, null, null, null, null],
      [null, null, null, null, null, null, null, null],
      [null, null, null, null, null, null, null, null],
      [null, null, null, null, null, null, null, null],
      [null, null, null, null, null, null, null, null],
      [null, null, null, null, null, null, null, null],
      [null, null, null, null, null, null, null, null],
      [null, null, null, null, null, null, null, null]
  ];
  </code></pre>
  
  <p>The compiler told me : </p>
  
  <blockquote>
    <p>Cannot convert {}[] to Entity[]</p>
  </blockquote>
  
  <p>Is this possible ? Am I doing something wrong.</p>
  
  <p>Thanks in advance !</p>
  
  <p>PS : Sorry for my english, I am not a native speaker.</p>