This compiles: instance (Typeable a, Arbitrary a, Typeable b, Arbitrary b, Convertible a b) => Arbitrary (Attr a b) where arbitrary = makeAttr `fmap` arbitrary coarbitrary a = error "Not implemented" arbitraryProp :: forall a b.(Eq a, Packet b, Show a, Convertible a b, Arbitrary a, Arbitrary b) => Gen (Attr a b) -> Gen Prop arbitraryProp attr = liftM2 (:=) attr arbitrary Joel On Oct 28, 2005, at 12:13 AM, Joel Reymont wrote:
Just one more question...
data Prop = forall a b. (Eq a, Eq b, Show a, Packet b, Convertible a b) => Attr a b := a deriving (Typeable)
data Attr a b = Attr String (a -> Dynamic, Dynamic -> Maybe a) (a -> b, b -> a)
makeAttr :: (Typeable a, Convertible a b) => String -> Attr a b makeAttr name = Attr name (toDyn, fromDynamic) (convert_AB, convert_BA)
I can do this for Attr
instance (Typeable a, Arbitrary a, Typeable b, Arbitrary b, Convertible a b) => Arbitrary (Attr a b) where arbitrary = makeAttr `fmap` arbitrary coarbitrary a = error "Not implemented"
How do I define an arbitrary prop, though? Following does not work:
arbitraryProp :: forall a b.(Arbitrary a, Arbitrary b) => Attr a b -
Gen Prop arbitraryProp = arbitrary := arbitrary