Thanks for all the suggestions, and the great work by Tillmann. I'll have a
look into the paper and the code, and try to see if it suits my needs.
Thanks!
2011/1/26 Tillmann Rendel
Hi Ozgur,
Ozgur Akgun wrote:
I can write (separately) a parser and a pretty-printer [...]
Is there any work to combine the two?
Brent Yorgey wrote:
Maybe take a look at "Invertible Syntax Descriptions: Unifying Parsing and Pretty Printing" by Tillmann Rendel and Klaus Ostermann from last year's Haskell Symposium:
http://www.informatik.uni-marburg.de/~rendel/unparse/
It's a beautiful paper, and perhaps the code will work for you (although it's too bad it's not on Hackage).
Indeed, I started this project for exactly the reason Ozgur describes: I needed to duplicate a lot of information between parsers and pretty printers and was annoyed about it. With invertible syntax descriptions, I now write a single program, which looks like a combinator parser (think "Parsec"), but can work as a pretty printer, too.
I just uploaded the code from the paper (and some additional combinators) to Hackage:
http://hackage.haskell.org/package/partial-isomorphisms http://hackage.haskell.org/package/invertible-syntax
I use this code for the implementation of some very small languages (think "lambda calculus"). This works fine.
I haven't really tried it for larger languages, but we have two students here in Marburg implementing a parser for Java using the library, so we are going to have experience with larger languages in a few weeks (months?).
If you give it a try, I would be happy to receive success stories, bug reports, patches, feature requests etc. I want to keep working on this, and I am open for suggestions.
Tillmann
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-- Ozgur Akgun