$x = { foo => "abc" };
$x .= { bar => "def", baz => "ghi" };

# I want $x to be:
# { foo => "abc", bar => "def", baz => "ghi" }

##</code><code>##

my $temp = { bar => "def", baz => "ghi" };
foreach my $key (keys %$temp) {
    $x->{$key} = $temp->{$key};
}