[Haskell-cafe] Foldable for BNFC generated tree

[Martijn van Steenbergen]

Hi Deniz,

Deniz Dogan wrote:
> So, basically I'd like some sort of folding functionality for these
> data types, without having to hack the lexer/parser myself
> (parameterising the data types), because as I said they're being
> generated by BNFC.

What exactly do you mean by folding functionality? Folding as in the 
Foldable type class applies to containers, which your data type isn't. 
Perhaps you're looking for generic programming?

There are several good GP libraries out there:

* EMGM: http://www.cs.uu.nl/wiki/GenericProgramming/EMGM
* Uniplate: http://community.haskell.org/~ndm/uniplate/
* SYB: http://www.cs.vu.nl/boilerplate/

See also Neil Mitchell's blog for some examples: 
http://neilmitchell.blogspot.com/2009/03/concise-generic-queries.html

HTH,

Martijn.