1 files changed, 60 insertions, 0 deletions
diff --git a/docs/examples/actors/Joins.scala b/docs/examples/actors/Joins.scala
new file mode 100644
index 0000000000..7ea2a50e11
--- /dev/null
+++ b/docs/examples/actors/Joins.scala
@@ -0,0 +1,60 @@
+package examples.actors
+
+import scala.actors.Actor._
+
+abstract class Producer[T] extends Iterator[T] {
+
+  protected def produce(x: T): unit = coordinator !? HasValue(x)
+  protected def produceValues: unit
+
+  def hasNext: boolean = { setCurrent(); !current.isEmpty }
+  def next: T = {
+    setCurrent()
+    val res = current.get
+    current = (coordinator !? Next()).asInstanceOf[Option[T]]
+    res
+  }
+
+  private var current: Option[T] = null
+  private def setCurrent() = if (current == null) current = (coordinator !? Next()).asInstanceOf[Option[T]]
+
+  private case class HasValue(value: T)
+  private case class Next
+  private case class Done
+  private case class Continue
+
+  /** A thread-based coordinator */
+  private val coordinator = actor {
+    while (true) {
+      receive {
+        case Next() =>
+          reply {
+            receive {
+              case HasValue(v) =>
+                reply()
+                Some(v)
+              case Done() =>
+                None
+            }
+          }
+      }
+    }
+  }
+
+  actor {
+    produceValues
+    coordinator !? Done()
+  }
+}
+
+object Joins extends Application {
+  def from(m: int, n: int) = new Producer[int] {
+    def produceValues = for (val i <- m until n) produce(i)
+  }
+
+  // note that it works from the main thread
+  val it = from(1, 10)
+  while (it.hasNext) {
+    Console.println(it.next)
+  }
+}