Hash merge/concatenation

Question

this is a dump of my hashes: %hash1

$VAR1 = {
    abc => {
        123 => [
          'xx',
          'yy',
          'zy'
        ],
        456 => [
          'ab',
          'cd',
          'ef'
        ]
    }
};

and the second one: %hash2

$VAR2 = { 
    def => {
        659 => [
            'wx',
            'yg',
            'kl'
        ],
        456 => [
            'as',
            'sd',
            'df'
        ]
    },
    abc => {
        987 => [
            'lk',
            'dm',
            'sd'
        ]
    }
};

Now I want to merge these two hashes in a new hash, but if a key is duplicated (here 'abc'), the values should be appended, not replaced, so the keys should remain unique, and all the values should be retained as well. How can this be done in Perl? The output should be as follows:

$VAR1 = {
    def => {
        659 => [
            'wx',
            'yg',
            'kl'
        ],
        456 => [
            'as',
            'sd',
            'df'
        ]
    },
    abc => {
        987 => [
            'lk',
            'dm',
            'sd'
        ],
        123 => [
            'xx',
            'yy',
            'zy'
        ],
        456 => [
            'ab',
            'cd',
            'ef'
        ]
    }
 };

Answer 1

Use the CPAN modules Hash::Merge or Hash::Merge::Simple. The first is highly configurable and the second is very simple to use.