ClosedFam1TH.hs:7:3: Warning:
    type family Foo_0 a_1 (b_2 :: k_3) where
    Foo_0 GHC.Types.Int GHC.Types.Bool = GHC.Types.Int
    Foo_0 a_4 GHC.Base.Maybe = GHC.Types.Bool
    Foo_0 b_5 (x_6 :: GHC.Types.Bool) = GHC.Types.Char