use constant foo =>{
                        key1 => val1,
                        key2 => val2
                    }

##</code><code>##

while(($key.$val) = each(foo))
{
   print $key{$val};
}

##</code><code>##

Ref  : HASH$VAR1 = {
          'key1' => val1,
           'key2' => val2
        };