Obfuscated Perl program

primes.pl

# Author: John Tromp <john.tromp@gmail.com>
# http://homepages.cwi.nl/~tromp/cl/cl.html
$|=1; $i=
sub{my$s=                  shift;
sub{                       shift->(
sub{my$n=                  shift;sub{$n}})->($s)}};$y=
sub{my$a=                  shift;my$q=
sub{my$t=                  shift;$a->(
sub{            $t->($t)->(shift)})};$q->($q)};$y->(
sub{my$a=                  shift;
sub{                       shift->(
sub{                  print(shift->('.')->('P'));
sub{                  $a->(shift)}})}})->($i->(($i)->($y->(
sub{my$p=                  shift;
sub{my$r=                  shift;my$s=
sub{my$i=                  shift;(
sub{my$m=                  shift;
sub{my$e=                  shift;
sub{                       shift->($m)->(
sub{      $e->($r->($i))->(shift)})}}})};
sub{                       shift->(sub{
sub{                       shift}})->(
sub{$p->($s)->($y->($s))->(shift)})}}})->(
sub{my$j=                  shift;sub{
sub{my$t=                  shift;$i->($t->($j))}}}))));