my $h = { 
    key1 => 'val1',
    key2 => { hash_ref2 => 'val2' },
    key3 => { hash_ref3 => { deeper => 'deep' , 
                             real_deep => { diving => 'now' } 
                           },
            },
    key4 => [ 'array ref1', 'array_ref2' ],
};
use Data::Dumper;
print Dumper $h;

rec_tree( $h );

sub rec_tree {
    my $val = shift;
    if ( ref($val) eq 'HASH' ) {
        rec_tree( $_ ) for values %$val;
    }
    elsif ( ref($val) eq 'ARRAY' ) {
        print "@$val\n";
    }
    else {
        # assume scalar as we are not dealing with other case
        # will stringify exceptions.....
        print $val, $/;
    }
}
__DATA__
$VAR1 = {
          'key1' => 'val1',
          'key2' => {
                      'hash_ref2' => 'val2'
                    },
          'key3' => {
                      'hash_ref3' => {
                                       'real_deep' => {
                                                        'diving' => 'now'
                                                      },
                                       'deeper' => 'deep'
                                     }
                    },
          'key4' => [
                      'array ref1',
                      'array_ref2'
                    ]
        };
val1
val2
now
deep
array ref1 array_ref2