interface Bag where
data Bag a {-# GHC_PRAGMA EmptyBag | UnitBag a | TwoBags (Bag a) (Bag a) | ListOfBags [Bag a] #-}
bagToList :: Bag a -> [a]
interface Bag where
data Bag a {-# GHC_PRAGMA EmptyBag | UnitBag a | TwoBags (Bag a) (Bag a) | ListOfBags [Bag a] #-}
bagToList :: Bag a -> [a]