All~
On Tue, 08 Feb 2005 17:51:24 +0100, Miroslav Silovic <[EMAIL PROTECTED]> wrote:
> [EMAIL PROTECTED] wrote:
>
> >>Well, we see the same kind of thing with standard interval arithmetic:
> >>
> >> (-1, 1) * (-1, 1) = (-1, 1)
> >> (-1, 1) ** 2 = [0, 1)
> >>
> >>The reason that junctions behave this way is because they don't
> >>collapse. You'll note the same semantics don't arise in
> >>Quantum::Entanglement (when you set the "try to be true" option).
> >>
> >>But you can force a collapse like this:
> >>
> >> my $x = 4 < $j;
> >> if $j < 2 { say "never executed" }
> >>
> >>
> >
> >By which I mean:
> >
> > my $x = 4 < $j;
> > if $x < 2 { say "never executed" }
> >
> >
> >
> Uh, I'm not sure this does what I think you wanted to say it does. ;) $x
> is a boolean, unless < returns a magical object... in which case, the
> magical part of $x ought to be a reference to the original $j, no?
>
> >>I'm wonding if we should allow a method that returns a junction that is
> >>allowed to collapse the original:
> >>
> >> if 4 < $j.collapse and $j.collapse < 2 {
> >> say "never executed";
> >> }
> >>
> >>But that's probably not a good idea, just by looking at the
> >>implementation complexity of Quantum::Entanglement. People will just
> >>have to learn that junctions don't obey ordering laws.
> >>
> >>
> Well, I suspect that junctions will have to be references and just
> collapse every time. Observe:
>
> my $x = any(1, 2, 3, 4, 5);
> print "SHOULD NOT RUN" if (is_prime($x) && is_even($x) && $x > 2);
>
> This only works if $x collapses. Same for matching junctioned strings:
>
> my $a = any (<a b c>);
> print "Boo!" if $a ~ /a/ and $a ~ /b/ and $a ~ /c/;
>
> (perhaps I meant to use ~~, I don't quite remember :) )
>
> Either way, autocollapsing juntions is a Good Thing IMHO, and the only
> remaining confusion (to go back to my initial post) is that the only
> case that doesn't work is when you instance a junction twice as a pair
> of same literals:
>
> print "SUCCESS, unfortunately" if (is_prime(any(1, 2, 3, 4, 5)) &&
> is_even(any(1, 2, 3, 4, 5)) && any(1, 2, 3, 4, 5) > 2);
>
> Hope I'm making sense. Been a hard day at work. ;)
What if junctions collapsed into junctions of the valid options under
some circumstances, so
my $x = any(1,2,3,4,5,6,7);
if(is_prime($x) # $x = any(2,3,5,7)
and is_even($x) # $x = any(2)
and $x > 2) # $x = any()
Matt
--
"Computer Science is merely the post-Turing Decline of Formal Systems Theory."
-???
