Hi,
I've been getting into Haskell over the past few months and have just come up against a bit of a brick wall when trying to encapsulate some of the data structures in my code nicely. Basically what I want to have, is a type class where one of the intermediate values is opaque with respect to code using its implementations. This is a simplified version of what I'm trying to accomplish:
class Foo t where encode :: String -> t decode :: t -> String
instance Foo Int where encode = read decode = show
test = decode . encode
This currently fails, because the type checker insists on trying to figure out what its type should be - even though it shouldn't be needed.
The intermediate type /is/ needed---it's a (hidden) parameter to your `encode' and `decode' functions. Why do you think it shouldn't be? <snip> Jon Cast