gistfile1.hs

  sha1 <- case (pgSelectedTab layout, rev) of
            (EditTab,Nothing) -> liftIO $ catch (latest fs $ pathForPage page)
                                                (\e -> if e == NotFound
                                                       then return ""
                                                       else throwIO e)
            (EditTab,Just r)  -> return r
            otherwise -> return ""
  let maybeSetSha1 | null sha1 = id
                   | otherwise = T.setAttribute "sha1" sha1
  let filledTemp = T.render $
                   maybeSetSha1 $
                   etc..