Re: [Haskell-cafe] Typeable typeclass and type-level naturals

On Wed, Jun 5, 2013 at 8:46 AM, Roman Cheplyaka wrote:

* TP [2013-06-05 00:37:36+0200]

...

Roman Cheplyaka wrote:

...

Try adding

deriving instance Typeable 'Zero deriving instance Typeable a => Typeable ('Succ a)

to your module.

(I haven't tested it -- you might need to tweak it a bit.)

Thanks Roman. Unfortunately, I already tried that (without the constraint "Typeable a =>", what a fool), but it did not work. The error is the same with the constraint:

Derived typeable instance must be of form (Typeable 'Succ) In the stand-alone deriving instance for 'Typeable a => Typeable (Succ a)'

What is the problem?

Oh, it should probably be simply

deriving instance Typeable 'Zero deriving instance Typeable 'Succ

Yes, that's how it should be. Please let me know if that doesn't work. (Sorry for taking so long to reply to this...) Cheers, Pedro

Roman

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