my @stuff = qw/ 9 -1 -3 hi 0 bye 5 10 /;

my $descending = 1;
my @ar;

if ( $descending ) {
       @ar = sort { num_or_str($b, $a) } @stuff;
}
else {
       @ar = sort { num_or_str($a, $b) } @stuff;
}