Kleisli and MonadTransformers

[Joheinz]

Hi *,

I can't find a function I am looking for, but can't believe it exists.
Let's say I have a Kleisli Arrow:

val foo = kleisli[Future, Int, String] { id =>
Future.successful(s"hello ${id}") }

I can tranform this into a

1) Kleisli[OptionT[Future, ?], Int, String] by using

foo.liftMK[OptionT]

But let's say my original foo would be

val foo = kleisli[Future, Int, Option[String]] { id =>
Future.successful(s"hello ${id}".some) }

and I want to transform this into something similiar as 1) How can I
do that? I also tried to write such a function, but I fail in getting
the evidence that the type parameter B of the Kleisli needs to be
something of N[_], where N is a Monad and then get a generic
MonadTransformer

The closest I achieved was a specialised version for OptionT:

implicit class KleisiTX[M[_], A, B](k: Kleisli[M, A, Option[B]]) {
def liftOptionT(implicit M: Monad[M]): Kleisli[OptionT[M, ?], A,
B] = Kleisli[OptionT[M, ?], A, B] {
(a: A) => OptionT[M, B](k.run(a))
}
}

However, I am still somehow convinced that such a function should already exist.
Regards
Markus