haskell-jp / random #92

-- barbies
class FunctorB (b :: (k -> Type) -> Type) where
  bmap :: (forall a . f a -> g a) -> b f -> b g

-- 自作
class FunctorB b where
  bmap :: (Functor f, Functor g) => (forall a. f a -> g a) -> b f -> b g

data Foo =
  Foo [(Bar, Buzz)]

data Foo f =
  Foo (f [f (f Bar, f Buzz)])

data Foo f =
  Foo (f [(bar, Buzz)])

Designing production applications in statically typed functional languages such as Haskell