Re: Types and "join compatibility"

"Marshall Spight" <marshall.spight_at_gmail.com> wrote in message news:1123082304.749632.295840_at_g44g2000cwa.googlegroups.com...

> In the same way:

> Let U = the universal set. U:U
> M intersect N = N minus (U minus M)
> type (M intersect N) = type (N minus (U minus M)) =
> type (M) union (type (U) union type M) =
> type (M) union (type U) =
> type (U)

> So the *real* answer is that the static type is the universal set.

Thank you !
I had this hunch a couple of years ago, but I didn't try to prove it.

Funny thing this "minus" operator :-)

> Alternatively, if we add two ints, we could come up with an
> equivalent expression that involves complex numbers. So the
> type of integer addition is complex!

> Again, I don't think this is a very good way to do things.

I agree. Received on Thu Aug 04 2005 - 09:53:37 CEST