1 files changed, 35 insertions, 0 deletions
diff --git a/docs/examples/patterns.scala b/docs/examples/patterns.scala
new file mode 100644
index 0000000000..34b0db96ae
--- /dev/null
+++ b/docs/examples/patterns.scala
@@ -0,0 +1,35 @@
+package examples;
+
+object patterns {
+
+  trait Tree;
+  case class Branch(left: Tree, right: Tree) extends Tree;
+  case class Leaf(x: Int) extends Tree;
+
+  val tree1 = Branch(Branch(Leaf(1), Leaf(2)), Branch(Leaf(3), Leaf(4)));
+
+  def sumLeaves(t: Tree): Int = t match {
+    case Branch(l, r) => sumLeaves(l) + sumLeaves(r)
+    case Leaf(x) => x
+  }
+
+  def find[a,b](it: Iterator[Pair[a, b]], x: a): Option[b] = {
+    var result: Option[b] = _;
+    while (it.hasNext && result == null) {
+      val Pair(x1, y) = it.next;
+      if (x == x1) result = Some(y)
+    }
+    if (result == null) None else result
+  }
+
+  def printFinds[a](xs: List[Pair[a, String]], x: a) =
+    find(xs.elements, x) match {
+      case Some(y) => System.out.println(y)
+      case None => System.out.println("no match")
+    }
+
+  def main(args: Array[String]): Unit = {
+    Console.println("sum of leafs=" + sumLeaves(tree1));
+    printFinds(List(Pair(3, "three"), Pair(4, "four")), 4)
+  }
+}
+\ No newline at end of file