title: Scala Nil equivalent for Set
body: <p>Is there an equivalent of <code>Nil</code> for <code>Set</code> in scala? </p>
  
  <p>I tried using <code>Nil</code> as a value for <code>Set</code>, but I got an error (expected since the type of <code>Nil</code> is <code>List</code>)</p>
  
  <p>Thanks</p>