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
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