Simon,
On 12/16/05, Simon Peyton-Jones
It's hard for me to do that. Except to say: look at the Info type
http://www.haskell.org/ghc/docs/latest/html/libraries/template-haskell/L anguage-Haskell-TH-Syntax.html#t%3AInfo
which tells you what reify returns.
OK, I was looking at "Dec" which has InstanceD, but "Info" does not have InstanceI, now I see. BTW is "Dec" for "Declaration"? All I would need is the fact that a particular instance was declared, nothing else.
The priority is low because few people ask, and because few people volunteer. It's a shame because it's a bit chicken-and-egg-ish. If TH was more complete, more people might use it.
Well, I felt some necessity when trying to implement the X11 protocol client side in Haskell: there are many C structures for which peek and poke methods could be easily generated via TH. But as I wrote in this particular case I have a workaround, albeit tool-specific. -- Dimitry Golubovsky Anywhere on the Web