DouKaku?

import    scala.concurrent.Lock
import    scala.concurrent.ops.spawn

object Main extends Application {
    var    l:Lock = new Lock
    var    r:Boolean = true
    var    q:Boolean = false
    
    def watch:Unit = {
        var    rec:Boolean = true
        try {
            l.acquire
            if (Console.in.ready) {
                Console.readLine.charAt(0) match {
                    case 'q' => {
                        r = false
                        q = true
                        rec = false
                    }
                    case 'p' => r = !r
                    case _ => Console.println("p[ENTER] :pause/resume\nq[ENTER] :quit")
                }
            }
        } catch {
            case e:StringIndexOutOfBoundsException => ()
            case e:Exception => {
                e.printStackTrace
                r = false
                q = true
                rec = false
            }
        } finally {
            l.release
        }
        if (rec) {
            Thread.sleep(100)
            watch
        }
    }
    
    def write:Unit = {
        var    rec:Boolean = true
        try {
            l.acquire
            if (r) Console.print('a')
            rec = !q
        } finally {
            l.release
        }
        if (rec) {
            Thread.sleep(1000)
            write
        }
    }
    
    spawn(watch)
    spawn(write)
}