title: Implicit conversion from List[Int] to List[Double] fails
body: <p>I am a Scala newbie and I've noticed a behaviour I do not understand. When I execute this code everything goes just fine:</p>
  
  <pre><code>val lD: List[Double] = List(1, 2, 3)
  </code></pre>
  
  <p>However when I execute this one:</p>
  
  <pre><code>val lI = List(1, 2, 3)
  val lD: List[Double] = lI
  </code></pre>
  
  <p>I get an error</p>
  
  <pre><code>&lt;console&gt;:11: error: type mismatch;
   found   : List[Int]
   required: List[Double]
  </code></pre>
  
  <p>May you please give me a clue why an implicit conversion does not take place in the second listing?</p>