[Haskell-cafe] Scheme in Haskell, Parsec Example, how to add scheme comments

[Berlin Brown]

I am sure many of you have looked at the scheme in haskell example that 
is on the web by Jonathan Tang. If you are familiar with the code, I 
need a little help trying to add scheme style comments:

"; This is my comment"

I added this code here and I think it works (I replaced the name 
parseSpaces with his "spaces" function).  But, if I start a line with a 
comment, it errors out with unbound variable.  Anybody have any ideas?

-- Added the ';'
symbol :: Parser Char
symbol = oneOf ";!$%&|*+-/:<=>?@^_~#\n"

--
-- Handle whitespace and comments
parseSpaces :: Parser ()
parseSpaces = (try oneLineComment) <|> whiteSpace <|> return ()
    where
      whiteSpace = do skipMany1 space
                      parseSpaces
      oneLineComment = do { try (string ";")
                          ; skipMany (satisfy (/= '\n'))
                          ; parseSpaces
                          }

http://halogen.note.amherst.edu/~jdtang/scheme_in_48/tutorial/overview.html