OrderServiceProvider.php

<?php

class OrderServiceProvider extends ServiceProvider
{
    public function register()
    {
        $this->app->bind(OrderProcessor::class, function ($app) {
            new OrderProcessor(
                [
                    new OrderHasAmount,
                    new OrderIsApproved,
                    new OrderIsNotCancelled
                ],
                $this->app->make(Slack::class)
            );
        });
    }
}