I'm not adverse to a purely intellectual challenge.

But the specification of what is and what is not zero doesn't seem to comply with any either real-world or rational definition that I can think of. I cannot think of any existing implementation that would interprete "0" as zero, and not "00" or "0 ". Nor can I see any rational for doing so.

Without some logic as to why these arbitrary rules have been picked, you might as well do:

#! perl -slw
use strict;
use feature qw[ state ];
use Scalar::Util qw[ dualvar ];


my @true = ( 0, "0", 0.0, Scalar::Util::dualvar( 0, 1 ) );
my @false = (
    1, "foo", "00", "0 ", undef, "",
    Scalar::Util::dualvar( 1, 0 ), "0.0"
);

sub isZero {
    state %isZero;
    unless( %isZero ) {
        $isZero{ $_ } = 1 for @true;
        $isZero{ $_ } = 0 for @false;
    }
    return $isZero{ $_ } if exists $isZero{ $_ };
    die "Don't know";
}


print "$_ : ", isZero( $_ ) for @true;
print "$_ : ", isZero( $_ ) for @false;
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As it can be infinitely extended to deal with any set of illogical rules.

Without some logic as to why these arbitrary rules have been picked,

Ok, here's the other part of the challenge: what's the logic about what for some people seem to be "arbitrary" or even "illogical"?