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  1. PO
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    <p>Scala does have FJ style parallelism. It's call futures and it's part of the actors library</p> <pre><code>import scala.actors.Future import scala.actors.Futures._ def mergeSort[A &lt;% Ordered[A]](xs : List[A]) : List[A] = { // merge is not interesting, it's sequential. The complexity lies in keeping it tail recursive def merge[A &lt;% Ordered[A]](accum : List[A], left : List[A], right : List[A]) : List[A] = { (left, right) match { case (lhead::ltail, rhead::rtail) =&gt; if (lhead &lt;= rhead) merge(lhead :: accum, ltail, right) else merge(rhead :: accum, left, rtail) case (Nil, _) =&gt; accum reverse_::: right case _ =&gt; accum reverse_::: left } } // here's the parallel sort bit def sort[A &lt;% Ordered[A]](xs : List[A], length : Int) : List[A] = { if (length &lt;= 1) xs else { val leftLength = length / 2 val rightLength = length - leftLength val (left, right) = xs splitAt leftLength // fork val leftFork = future { sort(left, leftLength) } val rightFork = future { sort(right, rightLength) } // join val leftJoin = leftFork() val rightJoin = rightFork() // merge merge(Nil, leftJoin, rightJoin) } } sort(xs, xs.length) } </code></pre> <p>Now, to the heart of the question. If Scala didn't have futures could you write one yourself based on actors. Indeed. It would look more or less like this.</p> <pre><code>import scala.actors.Actor import scala.actors.Actor._ object MyFuture { def apply[T](x : =&gt; T) : MyFuture[T] = { val future = new MyFuture[T] val act = actor { react { case sender : Actor =&gt; sender ! (future, x) } } act ! self future } } class MyFuture[A] extends Function0[A] { me =&gt; lazy val result = receive { case (`me`, result) =&gt; result.asInstanceOf[A] } def apply() = result </code></pre> <p>} </p> <p>And you would use it like so </p> <pre><code>scala&gt; val x = MyFuture(28 * 1000) x: Foo.MyFuture[Int] = &lt;function&gt; scala&gt; x() res4: Int = 28000 </code></pre>
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    1. POUsing scala actor framework as fork-join computation?
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    1. USJames Iry
    1. USJames Iry
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      1. VTUpMod
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    1. COWow, thank you.
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      1. USakarnokd
    2. COI tried your FJ example with list of size 400 and I don't get almost no cpu load (should be 100% on all cores, right?). Any exaplanation on that?
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      1. USawk
    3. COHow this can be rewritten with scala 2.10, where they discourage from using blocking future()?
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