Scala-machines Machine to Play Enumerator

conversion.scala

import com.clarifi.machines._

import play.api.libs.iteratee.{ Enumerator, Input, Iteratee }
import play.api.libs.concurrent.Execution.Implicits._

import scala.concurrent.Future

def simple[K, E](machine: Machine[K, E]): Enumerator[E] = new Enumerator[E] {
  def apply[A](start: Iteratee[E, A]): Future[Iteratee[E, A]] =   
     val result = machine.foldLeft(Future.successful(start)) { (future, value) ⇒
        future.flatMap(_.feed(Input.El(value)))
     }

      result.flatMap(_.feed(Input.EOF))
  }
}

def precise[K, E](machine: Machine[K, E]): Enumerator[E] = new Enumerator[E] {
  def apply[A](start: Iteratee[E, A]): Future[Iteratee[E, A]] = {
    def go(m: Machine[K, E], i: Iteratee[E, A]): Future[Iteratee[E, A]] = 
      i.fold {
        case Cont(k) ⇒ m match {
          case Return(_)         ⇒ sys.error("impossible situation")
          case Stop              ⇒ go(m, k(Input.EOF))
          case Await(_, _, next) ⇒ go(next(), i)
          case Emit(value, next) ⇒ go(next(), k(Input.El(value)))
        }
        case _ ⇒
          Future.successful(i)
    }

    go(machine, start)
  }
}