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

Berlin Brown berlin.brown at gmail.com
Sun Nov 18 19:32:56 EST 2007

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 ()
      whiteSpace = do skipMany1 space
      oneLineComment = do { try (string ";")
                          ; skipMany (satisfy (/= '\n'))
                          ; parseSpaces


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