Wow, what an old thread...
Jonadab the Unsightly One writes:
> "Abhijit A. Mahabal" <[EMAIL PROTECTED]> writes:
>
> > On the other hand, if you wanted to say "true for all except exactly
> > one value, I can't think of a way.
>
> Easy. The following two statements are equivalent:
>
> F(x) is true for all but exactly one x
> (not F(x)) is true for exactly one x
>
> The only additional possibility that can't be phrased in terms of the
> four given is the complex generalised case:
>
> F(x) is true for at least n but not more than m values of x
Oh, I wouldn't say that....
use HypotheticalModules::List::Combinations 束combinations損;
sub between($low, $high, [EMAIL PROTECTED]) {
any(
$low..$high ==> map -> $num {
any( map { all(@$_) } combinations($num, @values) )
}
)
}
Efficient? No. Blows out memory for (20, 30, 1..50)? Yes.
Works? Yes.
We also have:
class Betwunction is Junction {
submethod BUILD($.low, $.high, @.values) { }
method evaluate() {
my Int $n = grep { ? $_ } @.values;
$.low <= $n <= $.high;
}
}
sub between($low, $high, @values) {
new Betwunction: $low, $high, @values;
}
Or something. But I guess this one breaks the constraint of "in terms
of the four given".
> So for example you could have a list of fifty values for x and test
> whether the condition is true for at least ten but not more than
> fourty of them. (Or, x could be the condition; you could have a list
> of fifty conditions and test whether between twenty and thirty of them
> were true.) My guess is, however, that the frequency with which
> anyone would use such a capability would not be overwhelming.
>
> It would be great for obfuscation, though, particularly if some of the
> conditions had side effects with an impact on the value of the other
> conditions to be tested... That would be sufficiently interesting
> that it's almost a shame I can't think of a real reason to request
> such a feature, since I rather doubt anyone's going to much fancy
> implementing it just for obfuscatory value ;-)
Who needs reasons?
Luke
