title: Is eta reduction possible?
body: <p>Is it possible to apply eta reduction in below case?</p>
  
  <pre><code>let normalise = filter (\x -&gt; Data.Char.isLetter x || Data.Char.isSpace x )
  </code></pre>
  
  <p>I was expecting something like this to be possible:</p>
  
  <pre><code>let normalise = filter (Data.Char.isLetter || Data.Char.isSpace)
  </code></pre>
  
  <p>...but it is not</p>