ComposerServiceProvider.php

<?php
namespace App\Providers;
use Illuminate\Support\Facades\View;
use Illuminate\Support\ServiceProvider;
class ComposerServiceProvider extends ServiceProvider
{
    /**
     * Register bindings in the container.
     *
     * @return void
     */
    public function boot()
    {
        // Using Closure based composers...
        // Here is a simple example...
        View::composer('collections.index', function ($view) {
            $view->with('posts', app(\App\Services\PostService::class)->all());
        });
    }
    /**
     * Register the service provider.
     *
     * @return void
     */
    public function register()
    {
        //
    }
}