obj Foo has integer and real and string and boolean;

op MakeFoo(integer and real and string and boolean)->Foo;
op NotQuiteMakeFoo(integer and real and string and string)->Foo;

obj MakeFooType has op(integer and real and string and boolean)->(Foo);
obj NotQuiteMakeFooType has op(integer and real and string and string)->(Foo);

obj TupleOfMakeFoo has MakeFoo and MakeFoo;

op main(f:Foo, mft:MakeFooType, nqmft:NotQuiteMakeFooType) = (
    f = MakeFoo(1, 2.5, "xyz", true);
    mft = nqmft;		(* ERROR *)
    mft = NotQuiteMakeFoo;	(* ERROR *)
    mft = MakeFoo;		(* Why is this an ERROR? *)
    f = mft(1, 2.5, "xyz", true);
);