Not found and Missing parameters at Typesafe Stack getting started

Question

I was following the typesafe stack tutorial, and could not been able to resolve this:

> reload
[info] Building project Tutorial 1 1.0 against Scala 2.9.1
[info]    using TutorialOneProject with sbt 0.7.7 and Scala 2.7.7
> compile
[info] 
[info] == compile ==
[info]   Source analysis: 1 new/modified, 0 indirectly invalidated, 0 removed.
[info] Compiling main sources...
[error] /home/carlos/workspaces/scala/tutorial-1/src/main/scala/Pi.scala:3: not found: object Actor
[error] import Actor._
[error]        ^
[error] /home/carlos/workspaces/scala/tutorial-1/src/main/scala/Pi.scala:34: missing parameter type for expanded function
[error] The argument types of an anonymous function must be fully known. (SLS 8.5)
[error] Expected type was: ?
[error]     def receive = {
[error]                   ^
[error] /home/carlos/workspaces/scala/tutorial-1/src/main/scala/Pi.scala:58: missing parameter type for expanded function
[error] The argument types of an anonymous function must be fully known. (SLS 8.5)
[error] Expected type was: <error>
[error]     def receive: {
[error]                          ^
[error] three errors found
[info] == compile ==
[error] Error running compile: Compilation failed
[info] 
[info] Total time: 2 s, completed 07/02/2012 01:51:56

I was wondering too, why it says that its using scala 2.7.7 instead of 2.9.1...

My code are just as follows:

package akka.tutorial.first.scala

import Actor._
import akka._
import Routing._

import java.util.concurrent.CountDownLatch

object Pi extends App {

  calculate(nrOfWorkers = 4, nrOfElements = 10000, nrOfMessages = 10000)

  sealed trait PiMessage
  case object Calculate extends PiMessage
  case class Work(start: Int, nrOfElements: Int) extends PiMessage
  case class Result(value: Double) extends PiMessage

  class Worker extends Actor {

    def calculatePiFor(start: Int, nrOfElements: Int): Double = {
          var acc = 0.0
      for (i <- start until (start + nrOfElements))
        acc += 4.0 * (1 - (i % 2) * 2) / (2 * i + 1)
      acc
    }

    def receive = {
      case Work(start, nrOfElements) =>
        self reply Result(calculatePiFor(start, nrOfElements)) 
    }
  }

  class Master(
    nrOfWorkers: Int, nrOfMessages: Int, nrOfElements: Int, latch: CountDownLatch)
    extends Actor {

    var pi: Double = _
    var nrOfResults: Int = _
    var start: Long = _

    val workers = Vector.fill(nrOfWorkers)(actorOf[Worker].start())

    val router = Routing.loadBalancerActor(CyclicIterator(workers)).start()

    def receive: {
      case Calculate =>
        for (i <- 0 until nrOfMessages) router ! Work(i * nrOfElements, nrOfElements)

        router ! Broadcast(PoisonPill)

        router ! PoisonPill

      case Result(value) =>
        pi += value
        nrOfResults += 1
        if (nrOfResults == nrOfMessages) self.stop()
    }

    override def preStart() {
      start = System.currentTimeMillis
    }

    override def postStop() {
      println(
        "\n\tPi estimate: \t\t%s\n\tCalculation time: \t%s millis"
        .format(pi, (System.currentTimeMillis - start)))
      latch.countDown()
    }
  }

  def calculate(nrOfWorkers: Int, nrOfElements: Int, nrOfMessages: Int) {

    val latch = new CountDownLatch(1)

    val master = actorOf(
      new Master(nrOfWorkers, nrOfMessages, nrOfElements, latch)).start()

    master ! Calculate

    latch.await()
  }
}

I do know that the problem is something with types, but, I dont know scala so much, so, I dont know how to fix it.

Someone know how to fix this?

thanks in advance.

Answer 1

I just change my imports to:

import akka.actor.{Actor, PoisonPill}
import Actor._
import akka.routing.{Routing, CyclicIterator}
import Routing._
import akka.dispatch.Dispatchers

and it worked :)

thanks everyone.

Answer 2

Actor is a member of the akka package. Therefore you should reorder your import clauses such that the akka package comes first:

import akka._
import Actor._
import Routing._

Does that help?

By the way: The version of sbt (the build tool) you are using internally works with Scala 2.7.7 but your project is build against Scala 2.9.1. Please look at the full message ;-)