test.pl

sub filter(&@) {                                                                                                                                                                                                                             
  local $_;
  my ($code, $what) = @_;

  my $t = ref($what);

  if($t eq 'ARRAY'){
    for(my $i = 0; $i < @$what; ++$i){
      $_ = $what->[$i];
      splice(@$what, $i--, 1) unless $code->($what->[$i]); 
    }
  }elsif($t eq 'HASH'){
    foreach my $k (keys %$what){    
      $_ = $what->{$k};
      delete $what->{$k} unless $code->($k, $what->{$k});
    }
  }else{
    die("Don't know how to filter $t!");
  }

  $what;
}