Singletons/Operators.hs:(0,0)-(0,0): Splicing declarations
    singletons
      [d| child :: Foo -> Foo
          child FLeaf = FLeaf
          child (a :+: _) = a
          (+) :: Nat -> Nat -> Nat
          Zero + m = m
          (Succ n) + m = Succ (n + m)
          
          data Foo
            where
              FLeaf :: Foo
              (:+:) :: Foo -> Foo -> Foo |]
  ======>
    data Foo
      where
        FLeaf :: Foo
        (:+:) :: Foo -> Foo -> Foo
    child :: Foo -> Foo
    child FLeaf = FLeaf
    child (a :+: _) = a
    (+) :: Nat -> Nat -> Nat
    (+) Zero m = m
    (+) (Succ n) m = Succ (n + m)
    type FLeafSym0 = FLeaf
    type (:+:$$$) (t :: Foo) (t :: Foo) = (:+:) t t
    instance SuppressUnusedWarnings (:+:$$) where
      suppressUnusedWarnings _
        = snd ((GHC.Tuple.(,) (:+:$$###)) GHC.Tuple.())
    data (:+:$$) (l :: Foo) (l :: TyFun Foo Foo)
      = forall arg. SameKind (Apply ((:+:$$) l) arg) ((:+:$$$) l arg) =>
        (:+:$$###)
    type instance Apply ((:+:$$) l) l = (:+:) l l
    instance SuppressUnusedWarnings (:+:$) where
      suppressUnusedWarnings _
        = snd ((GHC.Tuple.(,) (:+:$###)) GHC.Tuple.())
    data (:+:$) (l :: TyFun Foo (TyFun Foo Foo -> GHC.Types.Type))
      = forall arg. SameKind (Apply (:+:$) arg) ((:+:$$) arg) =>
        (:+:$###)
    type instance Apply (:+:$) l = (:+:$$) l
    type (:+$$$) (t :: Nat) (t :: Nat) = (:+) t t
    instance SuppressUnusedWarnings (:+$$) where
      suppressUnusedWarnings _
        = snd ((GHC.Tuple.(,) (:+$$###)) GHC.Tuple.())
    data (:+$$) (l :: Nat) (l :: TyFun Nat Nat)
      = forall arg. SameKind (Apply ((:+$$) l) arg) ((:+$$$) l arg) =>
        (:+$$###)
    type instance Apply ((:+$$) l) l = (:+) l l
    instance SuppressUnusedWarnings (:+$) where
      suppressUnusedWarnings _
        = snd ((GHC.Tuple.(,) (:+$###)) GHC.Tuple.())
    data (:+$) (l :: TyFun Nat (TyFun Nat Nat -> GHC.Types.Type))
      = forall arg. SameKind (Apply (:+$) arg) ((:+$$) arg) => (:+$###)
    type instance Apply (:+$) l = (:+$$) l
    type ChildSym1 (t :: Foo) = Child t
    instance SuppressUnusedWarnings ChildSym0 where
      suppressUnusedWarnings _
        = snd ((GHC.Tuple.(,) ChildSym0KindInference) GHC.Tuple.())
    data ChildSym0 (l :: TyFun Foo Foo)
      = forall arg. SameKind (Apply ChildSym0 arg) (ChildSym1 arg) =>
        ChildSym0KindInference
    type instance Apply ChildSym0 l = Child l
    type family (:+) (a :: Nat) (a :: Nat) :: Nat where
      (:+) Zero m = m
      (:+) (Succ n) m = Apply SuccSym0 (Apply (Apply (:+$) n) m)
    type family Child (a :: Foo) :: Foo where
      Child FLeaf = FLeafSym0
      Child ((:+:) a _z_0123456789876543210) = a
    (%:+) ::
      forall (t :: Nat) (t :: Nat).
      Sing t -> Sing t -> Sing (Apply (Apply (:+$) t) t :: Nat)
    sChild ::
      forall (t :: Foo). Sing t -> Sing (Apply ChildSym0 t :: Foo)
    (%:+) SZero (sM :: Sing m) = sM
    (%:+) (SSucc (sN :: Sing n)) (sM :: Sing m)
      = (applySing ((singFun1 @SuccSym0) SSucc))
          ((applySing ((applySing ((singFun2 @(:+$)) (%:+))) sN)) sM)
    sChild SFLeaf = SFLeaf
    sChild ((:%+:) (sA :: Sing a) _) = sA
    data instance Sing (z :: Foo)
      = z ~ FLeaf => SFLeaf |
        forall (n :: Foo) (n :: Foo). z ~ (:+:) n n =>
        (:%+:) (Sing (n :: Foo)) (Sing (n :: Foo))
    type SFoo = (Sing :: Foo -> GHC.Types.Type)
    instance SingKind Foo where
      type Demote Foo = Foo
      fromSing SFLeaf = FLeaf
      fromSing ((:%+:) b b) = ((:+:) (fromSing b)) (fromSing b)
      toSing FLeaf = SomeSing SFLeaf
      toSing ((:+:) b b)
        = case
              (GHC.Tuple.(,) (toSing b :: SomeSing Foo))
                (toSing b :: SomeSing Foo)
          of {
            GHC.Tuple.(,) (SomeSing c) (SomeSing c)
              -> SomeSing (((:%+:) c) c) }
    instance SingI FLeaf where
      sing = SFLeaf
    instance (SingI n, SingI n) =>
             SingI ((:+:) (n :: Foo) (n :: Foo)) where
      sing = ((:%+:) sing) sing