title: Why do I get "expected class or object definition" when defining a type in scala?
body: <p>If I write something like this (to define Slick tables as per <a href="http://slick.typesafe.com/doc/2.1.0/orm-to-slick.html" rel="noreferrer">docs</a>):</p>
  
  <pre><code>type UserIdentity = (String, String)
  class UserIdentity(tag: Tag){
  ...
  }
  </code></pre>
  
  <p>I get a compile error: "expected class or object definition" pointing to the <code>type</code> declaration. Why?</p>