On Mon, 11 Jan 2016, Richard Eisenberg wrote:
On Jan 9, 2016, at 6:44 PM, Henning Thielemann <lemm...@henning-thielemann.de>
wrote:
instance (Natural n) => Num.Integer (Un n) where
type Repr (Un _n) = Unary
GHC-7.6.3 and GHC-7.4.2 complain:
Type indexes must match class instance head
Found `Un _n' but expected `Un n'
In the type synonym instance declaration for `Num.Repr'
In the instance declaration for `Num.Integer (Un n)'
GHC-7.8.4, GHC-7.10.3 and GHC-8.0 are happy with the difference.
I'm surprised this is accepted at all. Looks like hogwash to me. I think you
should post a bug report.
Ok, but then GHC must not warn about the unused argument of Repr.
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