Singletons/Empty.hs:(0,0)-(0,0): Splicing declarations
    singletons [d| data Empty |]
  ======>
    data Empty
    data instance Sing (z :: Empty)
    type SEmpty = (Sing :: Empty -> GHC.Types.Type)
    instance SingKind Empty where
      type DemoteRep Empty = Empty
      fromSing z
        = case z of {
            _ -> error "Empty case reached -- this should be impossible" }
      toSing z
        = case z of {
            _ -> error "Empty case reached -- this should be impossible" }