[Haskell-cafe] Re: Pickling HList

Joel Reymont joelr1 at gmail.com
Tue Nov 22 11:29:29 EST 2005


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)


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