My take on the Repository Pattern

Post_v1.php

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Model;

class Post extends Model
{
    /**
     * @var string The table where the posts are stored.
     */
    protected $table = 'posts';
}

PostController_v1.php

<?php

namespace App\Http\Controllers;

use Illuminate\Http\JsonResponse;
use App\Repositories\Contracts\PostRepository;

class PostController extends Controller
{
    /**
     * Construct the controller.
     *
     * @param PostRepository $repository The post repository.
     */
    public function __construct(PostRepository $repository) {
        $this->repository = $repository;
    }
  
    /**
     * Fetches all the posts.
     *
     * @param Request $request The post model.
     *
     * @return JsonResponse The response in JSON format.
     */
    public function index(Request $request) : JsonResponse
    {
        return $this->repository->all();
    }
  
    /**
     * Fetches a single post by its ID.
     *
     * @param Request $request The post model.
     * @param int     $id      The post primary identifier.
     *
     * @return JsonResponse The response in JSON format.
     */
    public function show(Request $request, int $id) : JsonResponse
    {
        return $this->repository->find($id);
    }
  
    /**
     * Stores a new post.
     *
     * @param Request $request The post model.
     *
     * @return JsonResponse The created post in JSON format.
     */
    public function store(Request $request) : JsonResponse
    {    
       return $this->repository->store($request->all());
    }
}

PostController_v2.php

<?php

namespace App\Http\Controllers;

use Illuminate\Http\JsonResponse;
use App\Repositories\Contracts\PostRepository;

class PostController extends Controller
{

    ...

    public function show(Request $request, int $id) : JsonResponse
    {
        $post = $this->repository->find($id);

        // So what if the Eloquent codebase changes?
        // What if retrieving attributes by value isn't supported anymore?
        // We need to update every bit of our application that's dependent on Eloquent.
        return [
            'id' => $post->id,
            'title' => $post->title,
            'description' => $post->description,
            'content' => $post->content,
        ];
    }

    ...

}

PostRepositoryContract_v1.php

<?php

namespace App\Repositories\Contracts;

use App\Models\Post;
use Illuminate\Support\Collection;

interface PostRepository extends Repository 
{
    /**
     * Fetches the post from it's primary identifier.
     *
     * @param int $id The primary identifier.
     *
     * @return Post The post model.
     */
    public function find(int $id) : Post;
  
    /**
     * Fetches all the available posts.
     *
     * @return Collection The collection with all the posts.
     */
    public function all() : Collection;
  
    /**
     * Stores a new post.
     *
     * @param mixed[] $attributes The attributes of the post.
     *
     * @return Post The created post.
     */
    public function store(array $attributes) : Post;
}

PostRepositoryContract_v2.php

<?php

namespace App\Repositories\Contracts;

use App\Entities\PostEntity;
use Illuminate\Support\Collection;

interface PostRepository extends Repository 
{
    /**
     * Fetches the post from it's primary identifier.
     *
     * @param int $id The primary identifier.
     *
     * @return PostEntity The post entity.
     */
    public function find(int $id) : PostEntity;

    /**
     * Fetches all the available posts.
     *
     * @return Collection The collection with all the posts.
     */
    public function all() : Collection;

    /**
     * Stores a new post.
     *
     * @param mixed[] $attributes The attributes of the post.
     *
     * @return PostEntity The created post entity.
     */
    public function store(array $attributes) : PostEntity;
}

PostRepositoryEloquent_v1.php

<?php

namespace App\Repositories\Eloquent;

use App\Repositories\Contracts\PostRepository as PostRepositoryContract;

class PostRepository extends Repository implements PostRepositoryContract
{
    /**
     * Construct the repository.
     *
     * @param Post $model The post Eloquent model.
     */
    public function __construct(Post $model) {
        $this->model = $model;
    }
  
    /**
     * {@inheritdoc}
     */
    public function find(int $id) : Post
    {
        return $this->model->find($id);
    }
    /**
     * {@inheritdoc}
     */
    public function all() : Collection
    {
        return $this->model->all();
    }
  
    /**
     * {@inheritdoc}
     */
    public function store(array $attributes) : Post
    {
        $post = new $this->model;
        $post->title = $attributes['title'];
        $post->description = $attributes['description'];
        $post->content = $attributes['content'];
        $post->save();

        return $post->fresh();
    }
}

PostRepositoryEloquent_v2.php

<?php

namespace App\Repositories\Eloquent;

use App\Repositories\Contracts\PostRepository as PostRepositoryContract;

class PostRepository extends Repository implements PostRepositoryContract
{

    ...

    // The find method returns an Eloquent model.
    // When switching to Doctrine, we need to update every instance that uses `$this->repository->find(...)`.
    public function find(int $id) : Post
    {
        return $this->model->find($id);
    }

    ...

}

PostRepositoryEloquent_v3.php

<?php

namespace App\Repositories\Eloquent;

use App\Repositories\Contracts\PostRepository as PostRepositoryContract;

class PostRepository extends Repository implements PostRepositoryContract
{
    /**
     * Construct the repository.
     *
     * @param Post $model The post Eloquent model.
     * @param Entity $entity The post entity.
     */
    public function __construct(Post $model, PostEntity $entity) {
        $this->model = $model;
        $this->entity = $entity;
    }

    /**
     * {@inheritdoc}
     */
    public function find(int $id) : PostEntity
    {
        return $this->model->find($id);
    }

    /**
     * {@inheritdoc}
     */
    public function all() : Collection
    {
        return $this->model->all();
    }

    /**
     * {@inheritdoc}
     */
    public function store(array $attributes) : Post
    {
        $post = new $this->model;
        $post->title = $attributes['title'];
        $post->description = $attributes['description'];
        $post->content = $attributes['content'];
        $post->save();

        return $post->fresh();
    }
}

RepositoryServiceProvider_v1.php

<?php

namespace App\Providers;

use App\Repositories\Eloquent\PostRepository;
use App\Repositories\Contracts\PostRepository as PostRepositoryContract;

class RepositoryServiceProvider extends ServiceProvider
{
    /**
     * @var mixed[] The array of repositories.
     */
    private $repositoryMapping = [
        PostRepositoryContract::class => PostRepository::class,
    ];

    /**
     * Bootstrap any application services.     
     */
    public function boot() : void
    {
        //
    }

    /**
     * Register any application services.
     */
    public function register() : void
    {
        foreach ($this->repositoryMapping as $contract => $instance)
        {
            $this->app->bind($contract, $instance);
        }
    }
}