A light weight Scala fork join syntax

Question

Despite the upcoming java 7 standard fork/join framework, I am building some helper method that is light weight in syntax for client to run code in parallel. Here is a runnable main method to illustrate the idea. ``` import actors.Futures object ForkTest2 { def main(args: Array[String]) { test1 test2 } def test1 { val (a, b, c) =fork({ Thread.sleep(500) println("inside fx1 ",+System.currentTimeMillis) true }, { Thread.sleep(1000) println("inside fx2 ",+System.currentTimeMillis) "stringResult" }, { Thread.sleep(1500) println("inside fx3 ",+System.currentTimeMillis) 1 }) println(b, a, c) true } def test2 { val results = forkAll({ () => Thread.sleep(500) println("inside fx1 ",+System.currentTimeMillis) true }, { () => Thread.sleep(1000) println("inside fx2 ",+System.currentTimeMillis) "stringResult" }, { () => Thread.sleep(1500) println("inside fx3 ",+System.currentTimeMillis) 1 }, { () => Thread.sleep(2000) println("inside fx4 ",+System.currentTimeMillis) 1.023 }) println(results) true…

Accepted Answer

Eric Torreborre wrote in the link provided by @retronym:

```
trait LazyParameters { 
  /** transform a value to a zero-arg function returning that value */ 
  implicit def toLazyParameter[T](value: =>T) = new LazyParameter(() => value) 
  /** class holding a value to be evaluated lazily */ 
  class LazyParameter[T](value: ()=>T) { 
    lazy val v = value() 
    def apply() = v 
  } 
} 
```

Here's LazyParameter version of your test:

```
object ForkTest2 extends LazyParameters {
```

...

```
def forkAll(fx1: LazyParameter[Any]*): List[Any] = {
  val results = fx1.toList.map {
    fx: LazyParameter[Any] => Futures.future(fx.apply())}
  Futures.awaitAll(tenMinutes, results: _*)
}
```

Edit: As you've noticed, implicit evaluates the by-name parameter and it doesn't carry forward the evaluation delay. Why not just use the word `future`? I personally think it makes the code more readable.

```
import actors.Futures
import actors.Futures.future
import actors.Future
```

...

```
def test2 {
  val results = forkAll(
    future {
      Thread.sleep(500)
      println("inside fx1 ",+System.currentTimeMillis)
      true
    },
    future {
      Thread.sleep(1000)
      println("inside fx2 ",+System.currentTimeMillis)
      "stringResult"
    },
    future {
      Thread.sleep(1500)
      println("inside fx3 ",+System.currentTimeMillis)
      1
    },
    future {
      Thread.sleep(2000)
      println("inside fx4 ",+System.currentTimeMillis)
      1.023
    })

println(results)
  true
}
```

...

```
def forkAll(futures: Future[Any]*): List[Any] = {
  println("forkAll")
  Futures.awaitAll(tenMinutes, futures: _*)
}
```

A light weight Scala fork join syntax

Solution

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