$services->set('indexBuilder')
  ->arg(
    '$indexName',
    expr("env('index_prefix') ~ '_' ~ parameter('main_index_name')"),
  );

use Symfony\Component\Security\Http\Attribute\IsGranted;

final class ViewPostController
{
  #[IsGranted('"ROLE_ADMIN" in roles or is_granted("VIEW", subject)', subject: 'post')]
  public function __invoke(Post $post): Response
  {
    return new Response('ok');
  }
}

$el = new ExpressionLanguage();

$sum = $el->evaluate('a + b', [
  'a' => 1,
  'b' => 2,
]);

$el = new ExpressionLanguage();

$isAGreatCustomer = $el->evaluate(
  '((100 * order.discount) / order.total) < 5',
  ['order' => $customer->getLastOrder()]),
);

$el = new ExpressionLanguage();

$ruleToBeEligible = <<<EOT
  placed_an_order_in(customer, 2022)
  &&
  is_registered_to_the_loyalty_program(customer)
  &&
  billing_address_located_in(customer, "France")
EOT;

$eligible = $el->evaluate(
  $ruleToBeEligible,
  ['customer' => $customer],
);

$el = new ExpressionLanguage();

$eligible = $el->evaluate(
  $rules->findEligibleForDiscount(),
  ['customer' => $customer],
);

new ExpressionFunction(

  name: 'is_registred_to_the_loyalty_program',
  
  compiler: static function (string $s): string {
    // ...
  },

  evaluator: static function (array $args, Customer $c): bool {
    return $args['loyaltyProgram']->registred->contains($c);
  },

)

final class LoyaltyProgramFunctionProvider implements ExpressionFunctionProviderInterface
{
    public function getFunctions(): array
    {
        return [
            new ExpressionFunction('is_registred_to_the_loyalty_program', ...),
            new ExpressionFunction(...),
            // ...
        ];
    }
}

use Symfony\Component\ExpressionLanguage\ExpressionLanguage as BaseEL;

final class ECommerceExpressionLanguage extends BaseEL
{
    public function __construct(
      CacheItemPoolInterface $cache = null,
      array $providers = [],
    ) {
        array_unshift($providers, new LoyaltyProgramFunctionProvider());
        array_unshift($providers, new CouponsFunctionProvider());

        parent::__construct($cache, $providers);
    }
}

$el = new ECommerceExpressionLanguage();

$ruleToBeEligible = <<<EOT
  placed_an_order_in(customer, 2022)
  && is_registered_to_the_loyalty_program(customer)
  && billing_address_located_in(customer, "France")'
EOT;

$eligible = $el->evaluate(
  $ruleToBeEligible,
  ['customer' => $customer],
);

final class UpdateIsEligibleForDiscountRuleAction extends AbstractController
{
  public function __invoke(ECommerceExpressionLanguage $el, RegleRepository $regles)
  {
    if ($form->isSubmitted() && $form->isValid()) {
      $regles->saveEligibleForDiscount($form->get('expression')->getData());
      
      return $this->redirectToRoute('rules');
    }

    return $this->render('update_is_eligible_for_discount_rule.html.twig', [
      'completion' => [
        ...array_map(
          fn ($f) => ['type' => 'function', 'label' => $f->getName()],
          $el->getFunctions(),
        ),
        ...array_map(
          fn ($v) => ['type' => 'variable', 'label' => $v],
          ['customer', 'loyaltyProgram'],
        ),
      ],
    ]);
  }
}

readonly final class ApplyDiscountCommandHandler
{
  public function __construct(
    private ECommerceExpressionLanguage $el,
    private RuleRepository $rules,
    private LoyaltyProgram $loyaltyProgram,
  ) {
  }

  public function __invoke(ApplyDiscountCommand $command): void
  {
    $eligible = $el->evaluate($rules->findEligibleForDiscount(), [
      'customer' => $command->customer,
      'loyaltyProgram' => $this->loyaltyProgram,
    ]);
    
    if (!$eligible) {
      return;
    }
    
    // ...
  }
}