1 files changed, 26 insertions, 0 deletions

diff --git a/stack/src/stack.ads b/stack/src/stack.ads
new file mode 100644
index 0000000..4f390e3
--- /dev/null
+++ b/stack/src/stack.ads
@@ -0,0 +1,26 @@
+generic
+   type T is private;
+package Stack is
+   type Stack is private;
+
+   -- Push a value into the stack.
+   procedure Push (S : in out Stack; Val : T);
+
+   -- Pop a value from the stack.
+   function Pop (S : in out Stack; Val : out T) return Boolean;
+
+   -- Return true if the stack is empty, false otherwise.
+   function Empty (S : Stack) return Boolean;
+private
+   type Node;
+   type Node_Access is access Node;
+
+   type Node is record
+      Val    : T;
+      Bottom : Node_Access;
+   end record;
+
+   type Stack is record
+      Top : Node_Access;
+   end record;
+end Stack;