map { $h{$_}++ == 0 ? $_ : () } @_;

Quote

The pure-Perl implementation of these functions only serves as a fallback in case the C portions of this module couldn't be compiled on this machine.

Always code as if the guy who ends up maintaining your code will be a violent psychopath who knows where you live. -- Damian Conway in "Perl Best Practices"
lesen: Wie frage ich & perlintro brian's Leitfaden für jedes Perl-Problem