Halting a Process[Task, O] on user input

Question

I am trying to write the following function ``` def haltOnUserInput[O](process: Process[Task, O]): Process[Task, O] ``` which halts `process` when the user sends a line on `stdin`. In this scenario, it is ok to wait for the current computation in the process to end, before ending the process itself. I have tried the following: ``` 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 } } ``` And I am testing like that: ``` 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 scal…

Accepted Answer

Another solution is to use 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
```

Halting a Process[Task, O] on user input

Solution

Problem