title: No instance for (Show a) arising
body: <p>ghci is giving me the error "No instance for (Show a) arising from use of 'commaSeperated'"</p>
  
  <p>What im trying to do is define a show for my data Set that uses curly braces instead of square. What am I doing wrong here?</p>
  
  <pre><code>data Set a = Set [a]
  
  instance Show (Set a) where
      show (Set a) = "{" ++ init (commaSeparated a) ++ "}"
  
  commaSeparated :: Show a =&gt; [a] -&gt; [Char]
  commaSeparated [] = ""
  commaSeparated (x:xs) = show x ++ "," ++ commaSeparated xs
  </code></pre>