暂停用户输入的进程[任务,O]

Question

我正在尝试编写以下函数

def haltOnUserInput[O](process: Process[Task, O]): Process[Task, O]

process当用户发送一行时停止stdin.在这种情况下,可以在结束进程本身之前等待进程中的当前计算结束.

我尝试过以下方法:

scala> :paste
// Entering paste mode (ctrl-D to finish)

import scalaz.{ -\/, \/-, \/ }
import scalaz.stream._
import scalaz.concurrent.Task

def haltOnUserInput[O](process: Process[Task, O]): Process[Task, O] = {
  process.either(io.stdInLines).flatMap {
    case -\/(o) => Process.emit(o)
    case \/-(_) => println("here"); Process.halt
  }
}

而我正在测试:

scala> val oneSec = scala.concurrent.duration.Duration("1s")
oneSec: scala.concurrent.duration.Duration = 1 second

scala> val test = haltOnUserInput(Process.awakeEvery(oneSec)).take(10).map(_.toString).to(io.stdOutLines).run
test: scalaz.concurrent.Task[Unit] = scalaz.concurrent.Task@7a5e41bb

scala> test.run
1000144294 nanoseconds
2000148316 nanoseconds
here
3000130736 nanoseconds
here
4000124898 nanoseconds
5000189134 nanoseconds
6000201269 nanoseconds
here
7000127797 nanoseconds
8000132194 nanoseconds
9000191001 nanoseconds
10000126974 nanoseconds

如您所见,用户输入已确认("此处"已打印多次)但Process不会中断.我不确定是否flatMap表现得像预期的那样Process.halt.

如何haltOnUserInput正确写？

Answer 1

另一个解决方案是使用 wye.interrupt：

val input = io.stdInLines.take(1).map(_ => true)
val dory = Process.awakeEvery(1.second).map(_ => println("Hi!"))
val process = input.wye(dory)(wye.interrupt)
process.run.run