obj T1 = integer and real and string and boolean;
obj T1n = i:integer and r:real and s:string and b:boolean;
obj T1n1 = i:integer and real and string and boolean;
obj T1n2 = i:integer and r:real and string and boolean;
obj T1n3 = i:integer and r:real and s:string and boolean;
obj T2 = integer and real and string and boolean;
obj T3 = T1 and T2;
obj T4 = integer or string;
obj T5 = string or integer;
obj T6 = string or boolean or integer;
obj T7 extends T1 = integer and real;
obj T8 extends T7 = boolean and string and string;

op Foo (t1:T1, t1n:T1n, t1n1:T1n1, t1n2:T1n2, t1n3:T1n3, t2:T2, t3:T3,
        t7:T7, t8:T8) = (
    t1 = t2;
    t1n = t2;
    t1n1 = t2;
    t1n2 = t2;
    t1n3 = t2;

    t1 = {1, 2.5, "xyz", true};
    t1 = {2.5, 1, "xyz", true};
    t1n = {1, 2.5, "xyz", true};
    t1n1 = {1, 2.5, "xyz", true};
    t3 = { {1, 2.5, "xyz", true}, {2, 3.5, "abc", false} };
    t3 = {t1, t2};
    t7 = {1, 2.5, "xyz", true, 2, 3.5};
    t8 = {1, 2.5, "xyz", true, 2, 3.5, true, "xyz2", "xyz3"};

    t1 = {1, 2.5, "xyz", true, 1};				(* ERROR *)
    t1 = {1, 2.5, "xyz"};					(* ERROR *)
    t1 = {1, 2.5, true, "xyz"};					(* ERROR *)
    t3 = { {1, 2.5, "xyz", true}, {2, 3.5, "abc", false}, 1 };	(* ERROR *)
    t3 = { {1, 2.5, "xyz", true}, {2, 3.5, "abc"} };		(* ERROR *)
    t3 = [ {1, 2.5, "xyz", true}, {2, 3.5, "abc", false} ];	(* ERROR *)
    t3 = {t1, t2, t1};						(* ERROR *)
    t7 = {2, 3.5, 1, 2.5, "xyz", true};				(* ERROR *)
);

(* These should be checked, but as of 22oct99 I don't think checking of
   tuple aggregates is done yet.  17jun09 update: they appear to work now. *)
val T:T3 = { {1, 2.5, "xyz", true}, {2, 3.5, "abc", false} };
val T':T3 = [ {1, 2.5, "xyz", true}, {2, 3.5, "abc", false} ];	(* ERROR *)

op FooOr(t4:T4, t5:T5) -> boolean = (
    t4 = t5;
    t4 = 10;
    t4 = "abc";
    t4 = false;		(* ERROR (since bool is not an alternative of T4) *)
);