Use Futures instead of Coroutines

Even for a coroutine we want to observe normal or anormal termination.
In that sense a Coroutine is really nothing but a Future[Unit].

Author: odersky

tests/run/suspend-strawman-2/channels.scala

@@ -97,33 +97,13 @@ object SyncChannel:
 
 end SyncChannel
 
-/** A simplistic coroutine. Error handling is still missing,  */
-class Coroutine(body: Async ?=> Unit)(using scheduler: Scheduler) extends Cancellable:
-  private var children: mutable.ListBuffer[Cancellable] = mutable.ListBuffer()
-  @volatile var cancelled = false
-
-  def cancel() =
-    cancelled = true
-    synchronized(children).foreach(_.cancel())
-
-  def addChild(child: Cancellable) = synchronized:
-    children += child
-
-  boundary [Unit]:
-    given Async = new Async.Impl(this, scheduler):
-      def checkCancellation() =
-        if cancelled then throw new CancellationException()
-    try body
-    catch case ex: CancellationException => ()
-end Coroutine
-
 def TestChannel(using Scheduler) =
   val c = SyncChannel[Option[Int]]()
-  Coroutine:
+  Future:
     for i <- 0 to 100 do
       c.send(Some(i))
       c.send(None)
-  Coroutine:
+  Future:
     var sum = 0
     def loop(): Unit =
       c.read() match