无形：抽象* arity并获取返回类型作为内部抽象类型成员的元组

Question

abstract class Test[T] {
  type Value
}

// This is wrong with respect to Scala syntax.
def fun(tests: Test[_]*): Tuple(tests(0)#Value, tests(1)#Value) = {
}

我想要的是对任意数量的var args的arity抽象，其中类型由抽象类型成员Value持有，如上所示。例如，从任何arity转到Product，从Product转到HList或其他任何东西，然后从那个转到元组。

def test[F, A, L, S, Rc <: Test[_]](f: F)(implicit ftp: FnToProduct.Aux[F, L => S],
  ev: S <:< Seq[Rc#Value]) {

  val sq = ev(ftp(f))

  // now I'd like to build a type to reference the return sequence in a tuple
  // What is the real way to do the below?
  type ReturnTpe = sq.foldLeft(HNil)((l, col) => col#Value :: l).tupled
}