obj X =  a:A and b:B and c:C;
obj Y =  a:A or b:B or c:C;
obj A;
obj B;
obj C;
var i: integer;

obj IntX < X where: A = integer; B = real; C = string; end;
obj IntY < Y where: A = integer; B = real; C = string; end;
obj Y1 < Y;
obj Y2 =  Y;

op main(ix:IntX, iy:IntY, y:Y, y1:Y1, y2:Y2) -> boolean = (
    
    y.a = nil;
    y?.a;

    y2?.a;
    y1?.a;
    iy?.a;
    iy.a = 10;
    iy.b = 10;
    iy.c = "xyz";

    iy.a = "xyz";	(* ERROR: iy.c is int, not string *)
    iy.b = "xyz";	(* ERROR: iy.c is real, not string *)
    iy.c = 10;		(* ERROR: iy.c is string, not int *)
    i?.a;		(* ERROR: just checking the obvious *)

    (*
     * Following lines just to reaffirm that tuples work right.
     *)
    ix.a = 10;
    ix.b = 10;
    ix.c = "xyz";

    ix.a = "xyz";	(* ERROR: ix.c is int, not string *)
    ix.b = "xyz";	(* ERROR: ix.c is real, not string *)
    ix.c = 10;		(* ERROR: ix.c is string, not int *)



);