title: What exactly did Scala improve with pattern matching in 2.10?
body: <p>I found it interesting that <a href="http://scalapuzzlers.com/index.html#pzzlr-002" rel="noreferrer">this puzzler</a>, specifically this code:</p>
  
  <pre><code>val (i, j): (Int, Int) = ("3", "4")
  </code></pre>
  
  <p>Fails at runtime in Scala 2.9.1, but fails at compile time w/ 2.10 M3(which is great).  I try to track what's coming in new Scala releases, but I'm unable to connect the dots here.  What improvement led to this more precise behavior?</p>