title: Not in scope 'foldrl'
body: <p>When trying to define the function</p>
  
  <pre><code>maximum' :: (Ord a) =&gt; [a] -&gt; a
  maximum' = foldrl (\x acc -&gt; if x &gt; acc then x else acc)
  </code></pre>
  
  <p>ghci reports the error:</p>
  
  <pre><code>Not in scope: `foldrl'
  Failed, modules loaded: none.
  Ubuntu 10.04
  $ ghci --version
  The Glorious Glasgow Haskell Compilation System, version 6.12.1
  </code></pre>
  
  <p>Why isn't the function <code>foldrl</code> in scope?</p>