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Diffstat (limited to 'tests/run/t603.scala')
-rw-r--r-- | tests/run/t603.scala | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/tests/run/t603.scala b/tests/run/t603.scala new file mode 100644 index 000000000..84a224a40 --- /dev/null +++ b/tests/run/t603.scala @@ -0,0 +1,35 @@ +object forceDelay { + import scala.language.implicitConversions + + class Susp[+A](lazyValue: => A) extends Function0[A] { + private var func: () => Any = () => lazyValue + private var value: Any = null + + override def apply() = { + if (func != null) { + value = func().asInstanceOf[A] + func = null + } + value.asInstanceOf[A] + } + + override def toString() = + if (func == null) "Susp(" + value + ")" + else "Susp(?)" + } + + def delay[A](value: => A) = new Susp[A](value) + implicit def force[A](s: Susp[A]): A = s() +} + +object Test { + import forceDelay._ + + def main(args: Array[String]) = { + val s: Susp[Int] = delay { Console.println("evaluating..."); 3 } + Console.println("s = " + s) + Console.println("s() = " + s()) + Console.println("s = " + s) + Console.println("2 + s = " + (2 + s)) + } +} |