use strict;
use Data::Dumper;

my $x = { a => 1, b => 2, aa => { aaa => 11 } };
print Dumper($x);

my $y = { c => 3, d => 4, aa => { bbb => 11 } };
print Dumper($y);

$x = { %$x, %$y };
print Dumper($x);


##</code><code>##

$VAR1 = { 'c' => 3,
          'a' => 1,
          'b' => 2,
          'd' => 4,
          'aa' => {
                    'bbb' => 11
                  }
        };

##</code><code>##

use Hash-Dumper qw/merge/;

##</code><code>##

$x = { %$x, %$y };

##</code><code>##

$x = merge( $x, $y );

##</code><code>##

$VAR1 = {
          'c' => 3,
          'a' => 1,
          'b' => 2,
          'd' => 4,
          'aa' => {
                    'bbb' => 11,
                    'aaa' => 11
                  }
        };