Marcin Kowalczyk wrote:
It would also be nice if both end-of-line comments and brace comments could be used for documentation purposes, since people clearly have different preferences. This suggets a convention which is similar for the two cases.
I don't think we should complicate the design and implementation for such case. Brace comments are used to insert a small comment in the middle of a line or comment out a large piece of code. I would stick to end-of-line comments for documentation purposes.
I don't think it is that complicated. When the lexer encounters a comment (end-of-line or brace), it checks whether the next token is a special tag. If so, we're in documentation mode, if not, we're not. Lexing in the two cases (as long as we're not supporting nested brace comments inside documentation, and I cannot see why one would like to do that) would be largely the same, with minor differences for handling line breaks/detecting the end of the documentation comment. So, regardless of whether we use positional cues or special marking for identifying the documentation comments, is there any really good reason for not allowing documentation comments in either of the two available Haskell commenting styles? If not, then maybe we can decide on allowing both and have one thing less to argue about! I guess people like Malcolm Wallace and Simon Marlow are in a good position to answer the above question. (For what it is worth: As long as there is some easy way for the lexer to recognize a documentation comment, I cannot see that supporting both styles would complicate the lexer in my (as far as scanning and parsing are concerned) Haskell compiler in any significant way.) In Jan Skibinski's module extractor, I believe the documentation comments are identified by the parser rather than the scanner. Jan, is that correct? If so, how much more difficult would it be to support both commenting styles in that case? Still, I think it would be good if the conventions are such that a lexer can recognize the documentation comments. Implementation issues apart, that would be consistent with the current design for pragmas which have a lot in common with documentation comments. Regards, /Henrik -- Henrik Nilsson Yale University Department of Computer Science nilsson@cs.yale.edu