Singletons/BoxUnBox.hs:(0,0)-(0,0): Splicing declarations
    singletons
      [d| unBox :: Box a -> a
          unBox (FBox a) = a
          
          data Box a = FBox a |]
  ======>
    data Box a = FBox a
    unBox :: Box a -> a
    unBox (FBox a) = a
    type FBoxSym0 :: forall a. (~>) a (Box a)
    data FBoxSym0 :: (~>) a (Box a)
      where
        FBoxSym0KindInference :: SameKind (Apply FBoxSym0 arg) (FBoxSym1 arg) =>
                                 FBoxSym0 a0123456789876543210
    type instance Apply FBoxSym0 a0123456789876543210 = FBox a0123456789876543210
    instance SuppressUnusedWarnings FBoxSym0 where
      suppressUnusedWarnings = snd ((,) FBoxSym0KindInference ())
    type FBoxSym1 :: forall a. a -> Box a
    type family FBoxSym1 (a0123456789876543210 :: a) :: Box a where
      FBoxSym1 a0123456789876543210 = FBox a0123456789876543210
    type UnBoxSym0 :: (~>) (Box a) a
    data UnBoxSym0 :: (~>) (Box a) a
      where
        UnBoxSym0KindInference :: SameKind (Apply UnBoxSym0 arg) (UnBoxSym1 arg) =>
                                  UnBoxSym0 a0123456789876543210
    type instance Apply UnBoxSym0 a0123456789876543210 = UnBox a0123456789876543210
    instance SuppressUnusedWarnings UnBoxSym0 where
      suppressUnusedWarnings = snd ((,) UnBoxSym0KindInference ())
    type UnBoxSym1 :: Box a -> a
    type family UnBoxSym1 (a0123456789876543210 :: Box a) :: a where
      UnBoxSym1 a0123456789876543210 = UnBox a0123456789876543210
    type UnBox :: Box a -> a
    type family UnBox (a :: Box a) :: a where
      UnBox (FBox a) = a
    sUnBox ::
      (forall (t :: Box a).
       Sing t -> Sing (Apply UnBoxSym0 t :: a) :: Type)
    sUnBox (SFBox (sA :: Sing a)) = sA
    instance SingI (UnBoxSym0 :: (~>) (Box a) a) where
      sing = singFun1 @UnBoxSym0 sUnBox
    data SBox :: forall a. Box a -> Type
      where
        SFBox :: forall a (n :: a). (Sing n) -> SBox (FBox n :: Box a)
    type instance Sing @(Box a) = SBox
    instance SingKind a => SingKind (Box a) where
      type Demote (Box a) = Box (Demote a)
      fromSing (SFBox b) = FBox (fromSing b)
      toSing (FBox (b :: Demote a))
        = case toSing b :: SomeSing a of SomeSing c -> SomeSing (SFBox c)
    instance SingI n => SingI (FBox (n :: a)) where
      sing = SFBox sing
    instance SingI1 FBox where
      liftSing = SFBox
    instance SingI (FBoxSym0 :: (~>) a (Box a)) where
      sing = singFun1 @FBoxSym0 SFBox