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authorPaul Phillips <paulp@improving.org>2012-05-03 17:11:30 -0700
committerPaul Phillips <paulp@improving.org>2012-05-03 17:15:31 -0700
commit8bc8b83f0bd7daef62b41b4a0c87b4e9b7344284 (patch)
tree4f445792891bd6945ce8132b97a0231a8cf54392 /test/files/run/reify_lazyevaluation.scala
parent58f6a1346093db2f407879246884d480ff8d7904 (diff)
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Moved passing tests from pending to files.
Most are pattern matcher bugs fixed by virtpatmat. A few are reifier, package object, or miscellaneous. I threw in an original test for SI-2337, to go with those for SI-1697, SI-3705, SI-4415, and SI-1357, all of which (in the interests of making sure this basket has all the eggs) I am closing.
Diffstat (limited to 'test/files/run/reify_lazyevaluation.scala')
-rw-r--r--test/files/run/reify_lazyevaluation.scala58
1 files changed, 58 insertions, 0 deletions
diff --git a/test/files/run/reify_lazyevaluation.scala b/test/files/run/reify_lazyevaluation.scala
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index 0000000000..1a0c858914
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+++ b/test/files/run/reify_lazyevaluation.scala
@@ -0,0 +1,58 @@
+import scala.reflect.mirror._
+
+object Test extends App {
+ reify {
+ object lazyLib {
+
+ /** Delay the evaluation of an expression until it is needed. */
+ def delay[A](value: => A): Susp[A] = new SuspImpl[A](value)
+
+ /** Get the value of a delayed expression. */
+ implicit def force[A](s: Susp[A]): A = s()
+
+ /**
+ * Data type of suspended computations. (The name froms from ML.)
+ */
+ abstract class Susp[+A] extends Function0[A]
+
+ /**
+ * Implementation of suspended computations, separated from the
+ * abstract class so that the type parameter can be invariant.
+ */
+ class SuspImpl[A](lazyValue: => A) extends Susp[A] {
+ private var maybeValue: Option[A] = None
+
+ override def apply() = maybeValue match {
+ case None =>
+ val value = lazyValue
+ maybeValue = Some(value)
+ value
+ case Some(value) =>
+ value
+ }
+
+ override def toString() = maybeValue match {
+ case None => "Susp(?)"
+ case Some(value) => "Susp(" + value + ")"
+ }
+ }
+ }
+
+ import lazyLib._
+
+ val s: Susp[Int] = delay { println("evaluating..."); 3 }
+
+ println("s = " + s) // show that s is unevaluated
+ println("s() = " + s()) // evaluate s
+ println("s = " + s) // show that the value is saved
+ println("2 + s = " + (2 + s)) // implicit call to force()
+
+ val sl = delay { Some(3) }
+ val sl1: Susp[Some[Int]] = sl
+ val sl2: Susp[Option[Int]] = sl1 // the type is covariant
+
+ println("sl2 = " + sl2)
+ println("sl2() = " + sl2())
+ println("sl2 = " + sl2)
+ }.eval
+}