Data update

Task/Stack/OCaml/stack.ml

@@ -0,0 +1,18 @@
+exception Stack_empty
+
+class ['a] stack =
+  object (self)
+    val mutable lst : 'a list = []
+
+    method push x =
+      lst <- x::lst
+
+    method pop =
+      match lst with
+        []    -> raise Stack_empty
+      | x::xs -> lst <- xs;
+                 x
+
+    method is_empty =
+      lst = []
+  end