use Data::Dumper;
$Data::Dumper::Deparse = 1;
$foo = sub {return []};
$bar = {arefpromise => $foo};
$d = Data::Dumper->new([$bar]);
print "foo is a coderef $foo returning ".$foo->()."\n";
$d->Seen ({$foo => $foo->()});
print $d->Dump();