It is possible to add translation abilities to any application object using specialized trait
Spiral\Translator\Traits\TranslatorTrait.
We can add the translator trait to the controller:
namespace App\Controller;
use Spiral\Translator\Traits\TranslatorTrait;
class HomeController
{
    use TranslatorTrait;
    public function index(): string
    {
        return $this->say('hello world!');
    }
}
Note
Run 'i18n:index' to index the string invocation.
In cases where a message defined by logic and can not be indexed use constants or properties to declare class messages,
every string wrapped with [[]] will be automatically indexed.
class HomeController 
{
   use TranslatorTrait;
   protected const MESSAGES = [
       'error'   => '[[An error]]',
       'success' => '[[Success]]'
   ];
   public function index(): string
   {
       echo $this->say(self::MESSAGES['error']);
   }
}