ClaimMondad version 1 - does not compile

RequestHeader.scala

import java.net.URI
import scalaz.concurrent.Promise
import scalaz._
import Scalaz._
import language.implicitConversions


case class Cert(cn: String, pubKey: BigInt, webids: List[URI] )

trait RequestHeader {
  type Certificates = Cert

  def cert: Promise[Claim[Certificates,_]]

}

trait Level
object Truth extends Level
object PubKeyVerified extends Level


trait Claim[S, L <: Level] {
  protected val statements: S

  val level: L

  // you might want a dedicated type for this verification functions
  // apart from the simple `Function1`... because then your intent will
  // become clear and you don't get any 'undesired' implicit values
  def verify[S2, L2 <: Level](implicit verify: Verificator[S, L, S2, L2]): Claim[S2,L2] =   {
    verify(this)
  }

  // ...
}

trait Verificator[S,L<: Level,S2,L2<:Level] {
  def apply(s: Claim[S,L]): Claim[S2,L2]
}




trait TrueClaim[S] extends Claim[S,Truth.type] {
  def st: S = statements
}

object Claim {

  implicit val level: Level =  Truth


//  implicit def truth[S](s: Claim[Truth.type,S]) =  s.flatMap(s => new TrueClaim[S] {
//      protected val statements = s
//      val level = Truth
//    }
//  )


  implicit def ClaimMonad[L <: Level](implicit lvl: L): Monad[({type f[+a] = Claim[a,L]})#f] =
   new Monad[({type f[+a] = Claim[a,L]})#f]  {

      def point[A](a: => A) = new Claim[A,L] {
        protected val statements : A = a

        val level: L = lvl

      }

      def bind[A, B](fa: Claim[A,L])(f: A => Claim[B,L]) = f(fa.statements)
    }

//  implicit def truthClaimMonad = ClaimMonad(Truth)
//  implicit def pubKeyVerifiedClaimMonad = ClaimMonad(PubKeyVerified)


}