如何在Scala中定义一个存在性更高的kinded类型

不幸的是,Scalac不允许这样做.

Welcome to Scala version 2.11.7 (Java HotSpot(TM) 64-Bit Server VM,Java 1.8.0_45).
Type in expressions to have them evaluated.
Type :help for more information.

scala> :paste
// Entering paste mode (ctrl-D to finish)

trait H[F[_,_]]
trait T[A,B]
val h:H[T] = null
val e:H[F] forSome { type F[A,B] } = h

// Exiting paste mode,now interpreting.

<console>:13: error: type mismatch;
 found   : H[T]
 required: H[_[A,B] <: Any]
Note: T <: Any,but trait H is invariant in type F.
You may wish to define F as +F instead. (SLS 4.5)
       val e:H[F] forSome { type F[A,B] } = h
                                             ^

我怎么能解决它？

无论类型参数是什么,我如何定义匹配任何H的类型？

更新：我甚至试图让Scalac推断出存在主义类型,但仍然不幸运.

Welcome to Scala version 2.11.7 (Java HotSpot(TM) 64-Bit Server VM,B]
val h:H[T] = null
trait T2[A,B]
val h2:H[T2] = null
Seq(h,h2)

// Exiting paste mode,now interpreting.

<console>:17: error: type mismatch;
 found   : H[T]
 required: H[_ >: T2 with T <: Object]
       Seq(h,h2)
           ^
<console>:17: error: type mismatch;
 found   : H[T2]
 required: H[_ >: T2 with T <: Object]
       Seq(h,h2)
              ^