On Wed, Nov 21, 2012 at 2:56 PM, Emil Axelsson wrote:
This is one of the problem Syntactic aims to solve, but it requires you to use a different representation of expressions (for good or bad). If you want to keep your existing representation, then you have to use a generic programming library that supports GADTs. I know at least the Spine approach supports GADTs, but the library on Hackage seems too incomplete to be useful:
http://hackage.haskell.org/package/spine
Just a comment on this library (since I put it up there). Yes, it is incomplete. It's only been used for students in a course. It is not intended for practical use.
Even if it were complete, the Type datatype is closed, meaning the library cannot be extended to support new types, which probably won't necessarily be that useful to you. The spine view works nicely as a model of SYB but not so nicely as a library for generic programming.
Regards,
Sean