use strict;
use warnings;

package joe;
my @names = ('joe', 'aaron');

package FP;
sub sortNames ($$)
{
    my ($x, $y) = @_;
    print "$x vs $y\n";
    return $x cmp $y;
}

package joe;
my @sorted = sort {FP::sortNames($a,$b)} @names;

print "sorted : @sorted\n";