1 files changed, 20 insertions, 0 deletions
diff --git a/tree.sml b/tree.sml
index ee82485..7209690 100644
--- a/tree.sml
+++ b/tree.sml
@@ -126,6 +126,26 @@ structure Tree: TREE = struct
     print' 0 t
   end
 
+  fun traverse Empty _ acc = acc
+    | traverse (Node (k, v, left, right)) f acc =
+    let
+      val acc = traverse left f acc
+      val acc = f k v acc
+      val acc = traverse right f acc
+    in
+      acc
+    end
+
+  fun changeV Empty _ = Empty
+    | changeV (Node (k, v, left, right)) f =
+    let
+      val left = changeV left f
+      val right = changeV right f
+      val v = f v
+    in
+      Node (k, v, left, right)
+    end
+
   fun size Empty = 0
     | size (Node(_, _, l, r)) = 1 + size l + size r
 end