Re: [Haskell-cafe] Non-derivable Typeable

Thanks, looking forward to it! Roman * José Pedro Magalhães [2013-01-22 14:41:25+0000]

Yes, that will work. But soon we'll have poly-kinded Typeable in HEAD, which will be able to derive that instance.

Cheers, Pedro

On Tue, Jan 22, 2013 at 2:34 PM, Roman Cheplyaka 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

* Roman Cheplyaka [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

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