DeriveFunctorMeh.hs

{-# LANGUAGE DeriveFunctor #-}

-- This are are fine
newtype F a = F ((a -> Bool) -> Bool) deriving Functor
newtype T a = T (a,a,a) deriving Functor

-- but if we define

newtype Fun a b   = Fun (a -> b) -- and
data    Tri a b c = Tri a b c

-- and try to
newtype F' a = F' (Fun (Fun a Bool) Bool) deriving Functor
newtype T' a = T' (Tri a a a) deriving Functor
-- then that will fail.

-- Meh.