[Haskell-cafe] the overlapping instance that wasn't?

[Michael Vanier]

  On 8/24/10 1:54 PM, Bartek Æwik³owski wrote:
> Hello Michael,
>
> This is because instance selection is solely based on instance heads,
> it doesn't consider contexts. There's a nice explanation available
> here: http://www.haskell.org/haskellwiki/GHC/AdvancedOverlap
>
> The fix in this case is very easy because there are only two cases
> (and you don't want to provide new Nat class instances):
>
> instance Show Z where
>      show _ = "0"
>
> instance Nat n =>  Show (S n) where
>      show _ = show $ toInt (undefined :: n) + 1
>
> regards,
> Bartek Æwik³owski
OK, thanks!

Mike