[Haskell-cafe] Non-derivable Typeable
José Pedro Magalhães
jpm at cs.uu.nl
Tue Jan 22 15:41:25 CET 2013
Yes, that will work. But soon we'll have poly-kinded Typeable in HEAD,
which will be able to derive that instance.
On Tue, Jan 22, 2013 at 2:34 PM, Roman Cheplyaka <roma at ro-che.info> wrote:
> I just found mkTyCon3 which generates the fingerprint automatically.
> (I was looking at Data.Typeable.Internal.mkTyCon before.)
> That answers my question.
> (Of course, a way to derive the instance would be even better...)
> * Roman Cheplyaka <roma at ro-che.info> [2013-01-22 15:28:55+0200]
> > I need to declare a Typeable instance for a type which has an argument
> > of kind * -> *. GHC refuses to derive it.
> > What is a recommended way to go about it?
> > In particular, if I write the instance by hand, how important is the
> > fingerprint, and how could I generate it?
> > Roman
> Haskell-Cafe mailing list
> Haskell-Cafe at haskell.org
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