| For example,
|
| module F(S,T) where
| type S a = (a,a)
| data T a = C a a
|
| could have the interface:
|
| interface F where
| type S a
| data T a
|
| Are there any problems with this?
The main difficulty is deciding whether the signatures in the
interface should be abstract or concrete. Suppose body of F was
f (x,y) b = if b then x else y
Now, should the interface say:
f :: S a -> a (a)
or
f :: (a,a) -> a (b)
This is not insuperable. Eg one might say (a) if you supply a signature,
with the defn of f, and (b) otherwise, but it is clearly an issue.
Simon
