Saved! You can share or revisit your program with this link:

The URL bar of your browser has also been updated to this link.

Toolbar controls:

Drop-down menus:

Tips and tricks:
{-# LANGUAGE DataKinds, TypeFamilies, FunctionalDependencies #-}
module Main where
import Data.Kind (Type)
data Tag = A | B | C
data STag tag where
SA :: STag A
SB :: STag B
SC :: STag C
-- class Fam (tag :: Tag) (t :: Type) | tag -> t where
-- instance {-# OVERLAPPABLE #-} Fam a Bool where
-- instance {-# INCOHERENT #-} Fam A Int where
type family Fam tag where
Fam A = Int
Fam _ = Bool
class Foo (tag :: Tag) where
foo :: STag tag -> Fam tag
instance Fam tag ~ Bool => Foo tag where
foo _ = True
instance Foo A where
foo _ = 42
main = print "hello"
-- foo :: forall tag a. STag tag -> Fam tag
-- foo SA = 42 :: Int
-- foo _ = True :: Bool
 
 
הההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההה
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX