gistfile1.txt

  def asyncTask(i: I)(implicit e: Executor): Task[O] = Task.suspend({
    Task.async { (cb: (Throwable \/ O) => Unit) =>
      Futures.addCallback(eval(i), new FutureCallback[O]() {
        def onSuccess(result: O) = {
          cb(result.right)
          self.onSuccess(result)
        }
        def onFailure(t: Throwable) = {
          cb(t.left)
          self.onFailure(t)
        }
      }, e)
    }
  })
  
  def syncTask(i: I)(implicit e: Executor): Task[O] = Task.suspend({
    val fo = eval(i)
    Futures.addCallback(fo, new FutureCallback[O]() {
      def onSuccess(result: O) = self.onSuccess(result)
      def onFailure(t: Throwable) = self.onFailure(t)
    }, e)
    Task(fo.get)
  })