MODULE Showcase9;
// Step 4.1 tour: procedures, value/VAR params, recursion,
// array + open-array params, strings through calls. Exit 140.
TYPE Vec = ARRAY [0..3] OF INTEGER;
VAR ExitCode : INTEGER;

PROCEDURE Double(n : INTEGER) : INTEGER;
BEGIN
  RETURN n * 2
END Double;

PROCEDURE Acc(VAR total : INTEGER; x : INTEGER);
BEGIN
  total := total + x
END Acc;

PROCEDURE Sum4(a : Vec) : INTEGER;
VAR i, s : INTEGER;
BEGIN
  s := 0;
  FOR i := 0 TO 3 DO s := s + a[i] END;
  RETURN s
END Sum4;

PROCEDURE Head(VAR a : ARRAY OF INTEGER) : INTEGER;
BEGIN
  RETURN a[0]
END Head;

PROCEDURE Fact(n : INTEGER) : INTEGER;
BEGIN
  IF n <= 1 THEN RETURN 1 END;
  RETURN n * Fact(n - 1)
END Fact;

VAR v : Vec;
VAR t : INTEGER;
BEGIN
  v[0] := 10; v[1] := 20; v[2] := 30; v[3] := 40;
  t := 0;
  Acc(t, Double(5));
  Acc(t, Sum4(v));
  Acc(t, Head(v));
  Acc(t, Fact(5) MOD 100);
  ExitCode := t
END Showcase9.