Hello! I was very surprised to see that Int and Integer seem to differ with respect to ambiguity. And I have no idea what is going on. This works as intended: data AW = AI Integer deriving (Show, Eq, Ord) class AWC a where toAW :: a -> AW fromAW :: AW -> a instance AWC Integer where toAW = AI fromAW (AI v) = v
toAW 5 5
However, the following gives an error: data AW = AI Int deriving (Show, Eq, Ord) class AWC a where toAW :: a -> AW fromAW :: AW -> a instance AWC Int where toAW = AI fromAW (AI v) = v
toAW 5 Ambiguous type variable 't' in the constraints: 'Num t' arising from the literal '5' 'AWC t' arising from the use of 'toAW'
Ok, I can fix this easily with
toAW (5::Int)
But I still don't understand what's going on? Why does one type work and the other does not? Is there a way around this without type annotations? Any hint would be greatly appreciated! Thanks in advance, Thomas