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  use strict;
  use SlidingList::Changes qw(find_new_elements);
...

  # And update our log with what we have seen
  push @log, @new;

package SlidingList::Changes;
use strict;
...

perl(1),
L<File::Tail> for a solution working only with files.

perl -MHTTP::Daemon -MHTTP::Response -MLWP::Simple -e ' ;    # The  
$d = new HTTP::Daemon and fork and getprint $d->url and exit;#spider
($c = $d->accept())->get_request(); $c->send_response( new   #in the
HTTP::Response(200,$_,$_,qq(Just another Perl hacker\n))); ' #  web