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

* 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 Roman