title: Haskell length + map explanation?
body: <p>I'm playing around with Haskell since I'm learning the language, and I just found something I don't understand and I can't find an explanation. If I try to run this code:</p>
  
  <pre><code>map (`div` 0) [1,2,3,4]
  </code></pre>
  
  <p>I get a divide by 0 exception, which is expected.
  But if I run this code:</p>
  
  <pre><code>length (map (`div` 0) [1,2,3,4])
  </code></pre>
  
  <p>I get 4! </p>
  
  <p>I'd like to know why I don't get the divide by 0 exception when I do the mapping inside the length function!</p>