Singletons/T229.hs:(0,0)-(0,0): Splicing declarations
    singletons
      [d| ___foo :: Bool -> Bool
          ___foo _ = True |]
  ======>
    ___foo :: Bool -> Bool
    ___foo _ = True
    type US___fooSym1 (t :: Bool) = US___foo t
    instance SuppressUnusedWarnings US___fooSym0 where
      suppressUnusedWarnings
        = snd ((GHC.Tuple.(,) US___fooSym0KindInference) GHC.Tuple.())
    data US___fooSym0 (l :: TyFun Bool Bool)
      = forall arg. SameKind (Apply US___fooSym0 arg) (US___fooSym1 arg) =>
        US___fooSym0KindInference
    type instance Apply US___fooSym0 l = US___foo l
    type family US___foo (a :: Bool) :: Bool where
      US___foo _ = TrueSym0
    ___sfoo ::
      forall (t :: Bool). Sing t -> Sing (Apply US___fooSym0 t :: Bool)
    ___sfoo _ = STrue