title: guard desugaring
body: <p>I often hear the phrase, guards are just syntactic sugar for if-then-else (or case statements).</p>
  
  <p>Can somebody please desugar the following instance:</p>
  
  <pre><code>halfOf :: Int -&gt; Int
  halfOf x | even x = div x 2
  </code></pre>
  
  <p>(The function is intentionally partial)</p>
  
  <p>Thanks,</p>