use Data::Dumper ();

my $foo = [1..5];
my $bar = [ [6..10], $foo ];

Data::Dumper::init_refaddr_format()              # Workaround
   if *Data::Dumper::init_refaddr_format{CODE};  # Backwards compat

my $d = Data::Dumper->new([ $bar ], [ '$bar' ]);
$d->Seen({ '$foo' => $foo });
print $d->Dump();

##</code><code>##

$bar = [
         [
           6,
           7,
           8,
           9,
           10
         ],
         $foo
       ];