use strict; use warnings; use Data::Dumper qw(Dumper); use YAML::XS qw(Dump); my $data = do { my $child = {}; my $parent = { child => $child }; $child->{parent} = $parent; }; print "#### Perl ####\n"; print Dumper($data), "\n"; print "#### YAML ####\n"; print Dump($data), "\n";