title: Extending generic typealias
body: <p>I have a generic typealias, for example</p>
  
  <pre><code>typealias StringArray = Array&lt;String&gt;
  </code></pre>
  
  <p>It is not possible to extend this like so:</p>
  
  <pre><code>extension StringArray {
      //Some methods
  }
  </code></pre>
  
  <p>But is it possible in another way or have I to write</p>
  
  <pre><code>extension Array where Element == String {
      //Some methods
  }
  </code></pre>
  
  <p>?</p>