MODULE Showcase23;
(* Showcase: a generic doubly linked list.  DList(T) is instantiated as
   IntList = DList(INTEGER); the program builds a list, walks it with
   Get(i), reverses it and sums it.  Prints, then exits with the sum. *)
IMPORT SysIO, IntList;
VAR l : IntList.List; i, sum, ExitCode : INTEGER;

PROCEDURE Show(pfx : ARRAY OF CHAR);
BEGIN
  SysIO.Write(pfx);
  i := 0;
  WHILE i < IntList.Count(l) DO
    SysIO.Write(" ");
    SysIO.WriteInt(IntList.Get(l, i));
    i := i + 1
  END;
  SysIO.WriteLn
END Show;

BEGIN
  IntList.Init(l);
  IntList.Append(l, 10);
  IntList.Append(l, 20);
  IntList.Prepend(l, 5);
  Show("list:");

  IntList.Reverse(l);
  Show("reversed:");

  sum := 0; i := 0;
  WHILE i < IntList.Count(l) DO
    sum := sum + IntList.Get(l, i);
    i := i + 1
  END;
  SysIO.Write("sum="); SysIO.WriteInt(sum); SysIO.WriteLn;
  ExitCode := sum                       (* 35 *)
END Showcase23.