title: Haskell parser error in where clause
body: <p>What is wrong with <code>rs</code> definition in first where section?</p>
  
  <pre><code>palindrome :: [a] -&gt; [a]
  
  palindrome xs = con xs rs
      where con a b = rev (rev a []) b
          rs = rev xs                        -- here
          where rev [] rs = rs
              rev (x:xs) rs = rev xs (x:rs)
  </code></pre>
  
  <p>I'm just learning Haskell but its syntax rules confuse me. The error message is</p>
  
  <pre><code>[1 of 1] Compiling Main             ( pelindrome.hs, interpreted )
  
  pelindrome.hs:5:8: parse error on input `rs'
  </code></pre>