Damian Conway wrote:
> > > Should I point out that RFC 225 (Superpositions) actually covers
> > > most of this?
> > >
> > > C<null> is equivalent in semantics to C<any()> or C<all()>.
> I hope you won't mind my pointing out that the documentation of the
> Quantum::Superpositions module -- to which the RFC also refers -- does
> provide a comprehensive exposition of superpositions.
>
> I take the liberty of reprinting it for you below.
Indeed. That is very helpful, although rather complex conceptually, I like the
power it brings to a simple syntax. It does appear that the equivalence stated is
correct, although the full implementation of RFC 225 would be more extensive than
that of the more limited RFC 263.
I can also imagine that a straightforward implementation of RFC 263 (one bit to
indicate distinguished value, overload the "actual value" field (which would be
otherwise unused) to indicate what type of distinguished value (undef, NULL) could
be extended to implement all 29 flavors of NULL that are known to relational
theorists. It is less clear that superpositions has an obvious extension to
multiple types of NULL. On the other hand, it is not clear that all 29 flavors of
NULL that are known to relational theorists are necessary, but I'd hate to preclude
them.
--
Glenn
=====
Even if you're on the right track,
you'll get run over if you just sit there.
-- Will Rogers
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