Going through the instances for HTypeable (http://www.haskell.org/HaXml/HaXml/src/Text/XML/HaXml/TypeMapping.html#toHType
) I saw the following instance for Either a b.
My question is, why doesn't the pattern match in the where clause
always fail? If (Left x) = m does not fail, doesn't that imply that m
is a Left x and therefore the (Right y) = m should fail?
thanks, max
instance (HTypeable a, HTypeable b) => HTypeable (Either a b) where
toHType m = Defined "Either" [hx, hy]
[ Constr "Left" [hx] [hx] {-Nothing-}
, Constr "Right" [hy] [hy] {-Nothing-}]
where (Left x) = m
(Right y) = m
hx = toHType x
hy = toHType y
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