Solve (?) task 2

tasks/task2.scala

@@ -0,0 +1,64 @@
+import scala.language.implicitConversions
+
+
+object Task2A {
+  implicit def voidDefToRunnable(f: () => Unit): Runnable
+    = new Runnable { override def run() = f() }
+
+  def makeThread(f: () => Unit): Thread = new Thread(f)
+}
+
+object Task2B extends App {
+  private var counter: Int = 0
+
+  def increaseCounter(): Unit = { counter += 1 }
+  def printCounter(): Unit = { println(counter) }
+
+  var x: Thread = Task2A.makeThread(increaseCounter)
+  var y: Thread = Task2A.makeThread(increaseCounter)
+
+  x.start()
+  y.start()
+  x.join()
+  y.join()
+
+  val z = Task2A.makeThread(printCounter)
+  z.start()
+  z.join()
+}
+
+object Task2C extends App {
+  private var counter: Int = 0
+
+  def increaseCounter() = {
+    counter.synchronized({ counter += 1})
+  }
+  def printCounter(): Unit = { println(counter) }
+
+  (1 to 5)
+  .map(x => {
+    val t = Task2A.makeThread(increaseCounter)
+    t.start()
+    t
+  })
+  .foreach(t => {
+    t.join()
+  })
+
+  val z = Task2A.makeThread(printCounter)
+  z.start()
+  z.join()
+}
+
+object Task2D extends App {
+  lazy val x: Unit = {
+    val t = Task2A.makeThread(() => {
+      println("locky locky")
+      println(x)
+    })
+    t.start()
+    t.join() // comment to potentially unlocky
+    ()
+  }
+  println(x)
+}