Singletons/Contains.hs:0:0: Splicing declarations
    singletons
      [d| contains :: Eq a => a -> [a] -> Bool
          contains _ [] = False
          contains elt (h : t) = (elt == h) || (contains elt t) |]
  ======>
    Singletons/Contains.hs:(0,0)-(0,0)
    contains :: forall a. Eq a => a -> [a] -> Bool
    contains _ GHC.Types.[] = False
    contains elt (h GHC.Types.: t) = ((elt == h) || (contains elt t))
    type instance Contains z GHC.Types.[] = False
    type instance Contains elt (GHC.Types.: h t) =
        :|| (:== elt h) (Contains elt t)
    type family Contains (a :: a) (a :: [a]) :: Bool
    sContains ::
      forall (t :: a) (t :: [a]). SEq (KProxy :: KProxy a) =>
      Sing t -> Sing t -> Sing (Contains t t)
    sContains _ SNil = SFalse
    sContains elt (SCons h t) = (%:||) ((%:==) elt h) (sContains elt t)