{-# LANGUAGE TypeFamilies #-}

class Foo a where data FooBar a

-- | Something.
class Bar a
  where
    -- | Bar bar
    data BarBar a
    -- | Bar baz
    data family BarBaz
        a

-- | Something more.
class Baz a where
    -- | Baz bar
    data BazBar
        a
        b
        c

    -- | Baz baz
    data family BazBaz
        b
        a
        c