Finding the most frequent words in Scala using Akka

Question

I'm new to akka and would like to get some feedback on my first attempt. The code takes text from stdin and finds the top 10 most frequently occurring words.

Specifically, I would like to know

1. Is passing the wordFrequencyAccumulator to the tokenizer a reasonable thing to do? Are there better alternatives?
2. Is the use of postStop in the WordFrequencyAccumulator to send the final result to the parent a reasonable thing to do? Are there better alternatives?
3. Anything else I might be doing that is weird or there is a better way?

import akka.actor._
import akka.routing._
import scala.io.Source
import scalaz._

import Scalaz._
import Utilities._

object WordCount {
  case class WordFrequencies(freq: Map[Token, Int])
}

class WordCount extends Actor {
  val wordFrequencyAccumulator = context.actorOf(Props[WordFrequencyAccumulator])

  val tokenizeProps = Props(new Tokenize(wordFrequencyAccumulator))
  val tokenizer = context.actorOf(RoundRobinPool(5).props(tokenizeProps))

  context.watch(tokenizer)

  Source.stdin.getLines.foreach(tokenizer ! _)
  tokenizer ! Broadcast(PoisonPill)

  def receive = {
    case WordCount.WordFrequencies(freq) =>
      freq.toList
        .sortWith(_._2 > _._2)
        .take(10)
        .foreach(println)
      context.stop(self)

    case Terminated(`tokenizer`) =>
      wordFrequencyAccumulator ! PoisonPill
  }
}

class Tokenize(wordFrequencyAccumulator: ActorRef) extends Actor {
  def receive = {
    case line: String =>
      val tokens = tokenize(line)
      val filteredTokens = tokens
        .filterNot(token => token.size < 3 || token.size > 45)
        .filterNot(stopWords)
      wordFrequencyAccumulator ! WordCount.WordFrequencies(frequencies(filteredTokens))
  }
}

class WordFrequencyAccumulator extends Actor {
  var frequencyAcc = Map[Token, Int]()

  def receive = {
    case WordCount.WordFrequencies(freq) => frequencyAcc = frequencyAcc |+| freq
  }

  override def postStop() = context.parent ! WordCount.WordFrequencies(frequencyAcc)
}