use Carp qw/croak/;
use List::Util qw/max/;

sub max_depth
{
	my $thing = shift;
	croak "too many arguments" if @_;
	
	my $children = do {
		if (ref $thing eq 'ARRAY')    { $thing }
		elsif (ref $thing eq 'HASH')  { [values %$thing] }
		else                          { undef }
	};
	
	return 1 + max map { max_depth($_) } @$children
		if $children;

	return 0;
}

my $data = {
	foo => [1, 2, 3],
	bar => [4, 5, { quux => { quuux => 6 } }],
	baz => 7,
	};

print max_depth($data->{bar}[2]{quux}{quxux}) . "\n";
print max_depth($data->{bar}[2]{quux}) . "\n";
print max_depth($data->{bar}[2]) . "\n";
print max_depth($data->{bar}) . "\n";
print max_depth($data) . "\n";

__END__
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