I've notice a behaviour of quickcheck that is unexpected to me. With
this code:
import Test.QuickCheck
main = check myconfig
((\v -> v == v) :: (Maybe Double,Maybe Double) -> Bool)
myconfig = defaultConfig{configMaxTest=100000,
configEvery = \n args -> show n ++ ":\n"
++ unlines args}
I am relying on the default Arbitrary instances to generate pairs of
maybe doubles. But to my surprise, all of the pairs have these patterns:
(Just _ Just _)
(Nothing, Nothing)
I never see patterns:
(Just _, Nothing)
(Nothing, Just _)
Why is this the case?
Thanks,
Tim
