MODULE Adder;
TYPE Cell; (
* Composite Type 
*)
  IN x,y,ci:BIT; (
* input signals 
*)
  OUT z,co:BIT; (
* output signals 
*) 
BEGIN
  z:=x-y-ci;
  co:=x
*y+x
*ci+y
*ci;
END Cell;
CONST N:=8;
IN X,Y:()BIT; ci:BIT; (
* input signals 
*)
OUT Z:()BIT; co:BIT; (
* output signals 
*)
VAR S:()Cell; (
* composite type instances 
*)
BEGIN
  S.0(X.0, Y.0, ci); (
* inputs in cell 0
*)
  FOR i:=1..N-1 DO
    S.i(X.i,Y.i,S().co); (
* inputs in cell i 
*)
  END;
  FOR i:=0..N-1 DO
    Z.i:=S.i.z;
END;
  co:=S.7.co;
END Adder.