title: Haskell: How to convert from IO (a) to a?
body: <p>I have a function that returns me <code>IO (Map.Map String Double)</code> and I need <code>Map.Map String Double</code>, without IO.</p>
  
  <p>I tried to do this, but it fails with: Not in scope: data constructor `IO'. </p>
  
  <pre><code>extractIO (IO (a)) = a
  </code></pre>