Schema::create('comments', function (Blueprint $table) {
            $table->increments('id');
            $table->unsignedInteger('user_id');
            $table->unsignedInteger('post_id');
            $table->unsignedInteger('reply_id')->default(0);
            $table->text('body');
            $table->timestamps();
        });

class Comment extends Model
{
    protected $fillable = [
        'user_id',
        'post_id',
        'reply_id',
        'body'
    ];

    public function user()
    {
        return $this->belongsTo(User::class);
    }

    public function post()
    {
        return $this->belongsTo(Post::class);
    }

    public function replies()
    {
        return $this->hasMany(Comment::class,'reply_id','id');
    }

$comments = Comment::with('replies')->where('reply_id','=',0)->get(['id','reply_id','body']);
   return response($comments);

public function replies() {
    return $this->hasMany('AppComment', 'parent_id');
}

@foreach($comments as $comment)
   {{ $comment->content }}

   @if ( $comment->replies )
       @foreach($comment->replies as $rep1)
           {{ $rep1->content }}
           ...
       @endforeach
   @endif
@endforeach