Singletons/T78.hs:(0,0)-(0,0): Splicing declarations
    singletons
      [d| foo :: MaybeBool -> Bool
          foo (Just False) = False
          foo (Just True) = True
          foo Nothing = False |]
  ======>
    foo :: MaybeBool -> Bool
    foo (Just False) = False
    foo (Just True) = True
    foo Nothing = False
    type FooSym1 (t :: Maybe Bool) = Foo t
    instance SuppressUnusedWarnings FooSym0 where
      suppressUnusedWarnings _
        = snd ((GHC.Tuple.(,) FooSym0KindInference) GHC.Tuple.())
    data FooSym0 (l :: TyFun (Maybe Bool) Bool)
      = forall arg. SameKind (Apply FooSym0 arg) (FooSym1 arg) =>
        FooSym0KindInference
    type instance Apply FooSym0 l = Foo l
    type family Foo (a :: Maybe Bool) :: Bool where
      Foo (Just False) = FalseSym0
      Foo (Just True) = TrueSym0
      Foo Nothing = FalseSym0
    sFoo ::
      forall (t :: Maybe Bool). Sing t -> Sing (Apply FooSym0 t :: Bool)
    sFoo (SJust SFalse) = SFalse
    sFoo (SJust STrue) = STrue
    sFoo SNothing = SFalse