title: Why can a Scala trait extend a class?
body: <p>I see that traits in Scala are similar to interfaces in Java (but interfaces in Java extend other interfaces, they don't extend a class). I saw <a href="https://stackoverflow.com/questions/1229743/scala-traits-usage">an example on SO about traits usage</a> where a trait extends a class.</p>
  
  <p>What is the purpose of this? Why can traits extend classes?</p>