Keean, I sort of gave up on HList for the time being since I found easier ways to solve my problem. Mainly, I could not estimate the impact it would have on run-time performance of my code and GHC not being able to compile the code was not a good indication. Simon PJ fixed that error since. My idea was to, basically, create my own record sans labels. I wanted to specify picklers and default values for each field instead. I have over 250 records, though, and some have over 10 fields. There is a lot of sharing of fields between the records but I still think this is too much for GHC to handle. Can you venture a guess on runtime performance of such code? Thanks, Joel On Nov 22, 2005, at 4:07 PM, Keean Schupke wrote:
hMarkAll Just hlist
class HList l => HMarkAll c l m | c l -> m where hMarkAll :: (forall a . a -> c a) -> l -> m instance HMarkAll c HNil HNil where hMarkAll _ _ = HNil instance HMarkAll c l m => HMarkAll c (HCons e l) (HCons (c e) m) where hMarkAll c (HCons e l) = HCons (c e) (hMarkAll c l)