Parsec (parser combinator)

I think this is quite cool. (Parsing an IRC 'NICK foo' message)

special = oneOf "-[]\\`^{}_" -- Taken from RFC1459, except '_',
                             -- which I added (generally accepted character (are there others?)).

nick = do { string "NICK"; space;
            first <- letter; rest <- many1 $ alphaNum <|> special; eof;
            return $ Nick (first:rest) }

Not quite sure what I think of it in comparison to regular expressions, yet.

>>4
You don't want to accept @, # or + as they have special meaning.