Singletons/T367.hs:(0,0)-(0,0): Splicing declarations
    singletonsOnly
      [d| const' :: a -> b -> a
          const' x _ = x |]
  ======>
    type Const'Sym2 (a0123456789876543210 :: a0123456789876543210) (a0123456789876543210 :: b0123456789876543210) =
        Const' a0123456789876543210 a0123456789876543210
    instance Data.Singletons.SuppressUnusedWarnings.SuppressUnusedWarnings (Const'Sym1 a0123456789876543210) where
      Data.Singletons.SuppressUnusedWarnings.suppressUnusedWarnings
        = snd (((,) Const'Sym1KindInference) ())
    data Const'Sym1 (a0123456789876543210 :: a0123456789876543210) :: forall b0123456789876543210.
                                                                      (~>) b0123456789876543210 a0123456789876543210
      where
        Const'Sym1KindInference :: forall a0123456789876543210
                                          a0123456789876543210
                                          arg. SameKind (Apply (Const'Sym1 a0123456789876543210) arg) (Const'Sym2 a0123456789876543210 arg) =>
                                   Const'Sym1 a0123456789876543210 a0123456789876543210
    type instance Apply (Const'Sym1 a0123456789876543210) a0123456789876543210 = Const' a0123456789876543210 a0123456789876543210
    instance Data.Singletons.SuppressUnusedWarnings.SuppressUnusedWarnings Const'Sym0 where
      Data.Singletons.SuppressUnusedWarnings.suppressUnusedWarnings
        = snd (((,) Const'Sym0KindInference) ())
    data Const'Sym0 :: forall a0123456789876543210
                              b0123456789876543210.
                       (~>) a0123456789876543210 ((~>) b0123456789876543210 a0123456789876543210)
      where
        Const'Sym0KindInference :: forall a0123456789876543210
                                          arg. SameKind (Apply Const'Sym0 arg) (Const'Sym1 arg) =>
                                   Const'Sym0 a0123456789876543210
    type instance Apply Const'Sym0 a0123456789876543210 = Const'Sym1 a0123456789876543210
    type family Const' (a :: a) (a :: b) :: a where
      Const' x _ = x
    sConst' ::
      forall a b (t :: a) (t :: b).
      Sing t -> Sing t -> Sing (Apply (Apply Const'Sym0 t) t :: a)
    sConst' (sX :: Sing x) _ = sX
    instance SingI (Const'Sym0 :: (~>) a ((~>) b a)) where
      sing = (singFun2 @Const'Sym0) sConst'
    instance SingI d => SingI (Const'Sym1 (d :: a) :: (~>) b a) where
      sing = (singFun1 @(Const'Sym1 (d :: a))) (sConst' (sing @d))