Singletons/EqInstances.hs:0:0: Splicing declarations
    singEqInstances [''Foo, ''Empty]
  ======>
    Singletons/EqInstances.hs:0:0:
    instance SEq (KProxy :: KProxy Foo) where
      (%:==) SFLeaf SFLeaf = STrue
      (%:==) SFLeaf ((:%+:) _ _) = SFalse
      (%:==) ((:%+:) _ _) SFLeaf = SFalse
      (%:==) ((:%+:) a a) ((:%+:) b b) = (%:&&) ((%:==) a b) ((%:==) a b)
    type family Equals_0123456789 (a :: Foo) (b :: Foo) :: Bool where
      Equals_0123456789 FLeaf FLeaf = True
      Equals_0123456789 ((:+:) a a) ((:+:) b b) = (:&&) ((==) a b) ((==) a b)
      Equals_0123456789 (a :: Foo) (b :: Foo) = False
    type instance (==) (a :: Foo) (b :: Foo) = Equals_0123456789 a b
    instance SEq (KProxy :: KProxy Empty) where
      (%:==) a _
        = case a of {
            _ -> error "Empty case reached -- this should be impossible" }
    type family Equals_0123456789 (a :: Empty)
                                  (b :: Empty) :: Bool where
      Equals_0123456789 (a :: Empty) (b :: Empty) = False
    type instance (==) (a :: Empty) (b :: Empty) = Equals_0123456789 a b