-- http://www.cs.nyu.edu/courses/summer07/G22.2110-001/hw06-ada-spec.txt
package Int_Stacks is
   type Int_Stack is private;
   function Create(Capacity : in Integer) return Int_Stack;
   procedure Push(S : in Int_Stack; N : Integer);
   function Pop(S : in Int_Stack) return Integer;
   function Size(S : in Int_Stack) return Integer;
   procedure Destroy(S : in out Int_Stack);
private
   type Int_Array_Value is array (Natural range <>) of Integer;
   type Int_Array is access Int_Array_Value;
   type Int_Stack_Value is record
      Size : Integer;
      Data : Int_Array;
   end record;
   type Int_Stack is access Int_Stack_Value;
end Int_Stacks;