A potential higher-kinded HttpService for BlueEyes

gistfile1.scala

import scalaz._
import scalaz.Scalaz._

trait Future[A]
object Future {
  def async[A](a: A): Future[A] = error("todo")
}

sealed trait NotServed

case class HttpRequest[A](content: Option[A])

sealed abstract class HttpService[A, B, +M[_]: Functor] { self =>
  def service: HttpRequest[A] => M[B] = error("todo")
  
  def map[C](f: B => C): HttpService[A, C, M] = new HttpService[A, C, M] {
    override val service = (r: HttpRequest[A]) => self.service(r).map(f)
  }
  
  def mmap[N[_]: Functor](f: M[B] => N[B]): HttpService[A, B, N] = new HttpService[A, B, N] {    
    override val service = (r: HttpRequest[A]) => f(self.service(r))
  }

  def contramap[C](f: C => A): HttpService[C, B, M] = new HttpService[C, B, M] {
    override val service = (r: HttpRequest[C]) => self.service(r.copy(content = r.content.map(f)))
  }
  
  def ~ [X[V] <: Validation[NotServed, V]](other: HttpService[A, B, X])(implicit ev: M[B] <:< X[B], f: Functor[X]) = OrService[A, B](self.mmap(ev), other)
}

case class OrService[A, B](services: HttpService[A, B, ({type X[B] = Validation[NotServed, B]})#X]*) extends HttpService[A, B, ({type X[B] = Validation[NotServed, B]})#X]

case class AsyncService[A, B, M[_]: Functor](delegate: HttpService[A, B, M]) extends HttpService[A, Future[B], M] {
  override def service: HttpRequest[A] => M[Future[B]] = (r: HttpRequest[A]) => delegate.map(Future.async).service(r)
}

abstract class Service[A, B, R[A], S[B], +M[_]: Functor] { self =>
def service: R[A] => Validation[NotServed, S[B]]

def map[C](f: B => C): HttpService[A, C, R[A], S[B], M] = new HttpService[A, C, R[C], S[M], M] {
override val service = (r: R[A]) => self.service(r).map(f)
}
}

abstract class HttpService[A, B, +M[_]: Functor] extends Service[A, B, HttpRequest[A], ({type λ[α] = B})#λ, M]