a.hs

{-# LANGUAGE RankNTypes, DerivingStrategies, GeneralizedNewtypeDeriving #-}

-- Defaults to newtype
newtype T_Def = T_Def Bool
  deriving (Eq, Ord, Bounded)

-- Stock
newtype T_S = T_S Bool
  deriving stock (Eq, Ord, Bounded)

-- Newtype
newtype T_NT = T_NT Bool
  deriving newtype (Eq, Ord, Bounded)

-- Defaults to newtype (unless DeriveFunctor or DeriveFoldable are on)
newtype F_NT a = F_NT (Either Int a)
  deriving (Functor, Foldable)

-- Defaults to newtype, fails
-- newtype F_NT_BAD a = F_NT_BAD (forall r. Either r a)
--   deriving (Functor, Foldable)

main = return ()