KleisliHttpApp.scala

type Http[F[_]] = Kleisli[F, Request, Response]

type HttpApp = Http[Future]

object HttpApp {
  def apply(f: Request => Future[Response]): HttpApp =
    Kleisli(f)
}

case class OptionFuture[A](value: Option[Future[A]])

type HttpRoutes = Http[OptionFuture]

object HttpRoutes {
  def of(pf: PartialFunction[Request, Future[Response]]): HttpRoutes =
    Kleisli(pf.lift.andThen(OptionFuture(_)))
}