title: How to filter by type in Ceylon in an elegant way?
body: <p>I was hoping the following would work:</p>
  
  <pre><code>void takeOnlyStrings(String* s) {
     print(s);
  }
  
  {String|Integer*} ab = {"Hi", 1};
  
  takeOnlyStrings(for (item in ab) if (item is String) item);
  </code></pre>
  
  <p>Or even this:</p>
  
  <pre><code>Boolean isString(Object o) =&gt; (o is String);
  takeOnlyStrings(ab.filter(isString));
  </code></pre>
  
  <p>But no luck.</p>