是否可以通过另一个类型构造函数派生一个Traversable实例？

假设我们有一个类，Foo这样的实例Foo f为我们提供了实现Functor f,Foldable f和所需的一切Traversable f。为了避免重叠实例，可以在 newtype 包装器之间Foo和Functor, Foldable, Traversable下见证这种关系：

type Foo :: (Type -> Type) -> Constraint
class Foo f
  where
  {- ... -}

type FoonessOf :: (Type -> Type) -> Type -> Type
newtype FoonessOf f a = FoonessOf (f a)

instance Foo f => Functor (FoonessOf f)
  where
  fmap = _

instance Foo f => Foldable (FoonessOf f)
  where
  foldMap = _

instance Foo f => Traversable (FoonessOf f)
  where
  traverse = _

现在假设我们有一些类型构造函数：

data Bar a = Bar {- ... -}

这样有一个：

instance Foo Bar
  where
  {- ... -}

我们想配备Bar它的“ Foo-ness”所隐含的实例。既然Bar a是Coercible要FoonessOf Bar a，我们就希望能够推导实例via的FoonessOf Bar：

deriving via (FoonessOf Bar) instance Functor Bar
deriving via (FoonessOf Bar) instance Foldable Bar

这适用于类型类，例如Functor和Foldable

不幸的是，当我们尝试用 做同样的事情时Traversable，事情会出错：

[typecheck -Wdeferred-type-errors] [E] • Couldn't match representation of type ‘f1 (Foo Bar a1)’
                           with that of ‘f1 (Bar a1)’
    arising from a use of ‘ghc-prim-0.6.1:GHC.Prim.coerce’
  NB: We cannot know what roles the parameters to ‘f1’ have;
    we must assume that the role is nominal
• In the expression:
      ghc-prim-0.6.1:GHC.Prim.coerce
        @(Foo Bar (f a) -> f (Foo Bar a)) @(Bar (f a) -> f (Bar a))
        (sequenceA @(Foo Bar)) ::
        forall (f :: TYPE ghc-prim-0.6.1:GHC.Types.LiftedRep
                     -> TYPE ghc-prim-0.6.1:GHC.Types.LiftedRep)
               (a :: TYPE ghc-prim-0.6.1:GHC.Types.LiftedRep).
        Applicative f => Bar (f a) -> f (Bar a)
  In an equation for ‘sequenceA’:
      sequenceA
        = ghc-prim-0.6.1:GHC.Prim.coerce
            @(Foo Bar (f a) -> f (Foo Bar a)) @(Bar (f a) -> f (Bar a))
            (sequenceA @(Foo Bar)) ::
            forall (f :: TYPE ghc-prim-0.6.1:GHC.Types.LiftedRep
                         -> TYPE ghc-prim-0.6.1:GHC.Types.LiftedRep)
                   (a :: TYPE ghc-prim-0.6.1:GHC.Types.LiftedRep).
            Applicative f => Bar (f a) -> f (Bar a)
  When typechecking the code for ‘sequenceA’
    in a derived instance for ‘Traversable Bar’:
    To see the code I am typechecking, use -ddump-deriv
  In the instance declaration for ‘Traversable Bar’
——————————————————————————————————————————————————————————————————————————————
...

所以我的问题是：

1. 是否有可能想出一些其他的通过实例派生的方案Traversable Bar？
2. 是否可以对Traversable可以通过 newtype 派生的类进行一些修改？