title: Haskell Maybe Int to Int
body: <p>I have a function where <code>n</code> needs to be an <code>Int</code> but is a <code>Maybe Int</code>; how could I convert this? I'm aware that this has been asked before, but I don't understand the answer.</p>
  
  <pre><code>where n = case elemIndex column header of
          Nothing -&gt; Nothing
          Just n  -&gt; n
  </code></pre>