On Sun, 2007-11-18 at 19:37 -0500, Berlin Brown wrote:
> On Nov 18, 2007 7:32 PM, Berlin Brown <[EMAIL PROTECTED]> wrote:
> > 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"
The preferred way to do that is to use a token helper function:
token :: P a -> P a
token p = do r <- p
whiteSpace
return r
-- or, if you add a Control.Applicative instance for your
-- parser type, this is just: token p = p <* whiteSpace
Then you handle comments as whitespace:
whiteSpace :: P ()
whiteSpace = skipMany $
spaces
<|> (char ';' >> skipMany (satisfy (/='\n')))
Then you just use that like this:
symbol :: P String
symbol = token $ many1 $ satisfy $ not . (`elem` "()[]; ")
See also Parsec's TokenParser.
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