Ticket #163 (new defect)
Opened 4 years ago
Elaboration of class constructors isn't respecting their kinds
|Reported by:||benl||Owned by:|
This program should work
class Bag (bag :: % -> * -> *) where size :: forall a %r1 %r2 . bag %r1 a -(!e1)> Int %r2 :- !e1 = !Read %r1 instance Bag List where size = length main () = println $ show $ size [1, 2, 3];
In the class instance, List has the correct kind, but it's being elaborated to:
instance Bag (List %r1) where size = length
which is now an error because (List %r1) has kind * -> * and not % -> * -> *.
The elaborator shouldn't have added the %r1 because that type expression already had the correct kind.