title: Why are Arrays invariant, but Lists covariant?
body: <p>E.g. why does</p>
  
  <pre><code>val list:List[Any] = List[Int](1,2,3)
  </code></pre>
  
  <p>work, but</p>
  
  <pre><code>val arr:Array[Any] = Array[Int](1,2,3)
  </code></pre>
  
  <p>fails (because arrays are invariant). What is the desired effect behind this design decision?</p>