Anonymous function inside PHP array?

Question

PHP

Below is the code where the nav() method returns the processed data.
The problem is with the anonymous function. It is necessary for me in this order that the script would work out and return the data, as in js. Where are the errors in the code or is it not possible?
Mistake:

Catchable fatal error: Object of class Closure could not be converted to string in

<?
class header {

    public function nav (){

        return view::tpl('header', array (
            'navigation' => function (){

                $sql = sql::getInstance();

                // Получаем список модулей
                $sql->where('nav', 'head');
                $modules = $sql->get('modules', null, array('name', 'module', 'nav'));

                foreach ($modules as $module){
                    view::tpl('header-nav',array(
                        'name'    => $module['name'],
                        'link'    => $module['module'],
                        'class'   => router::$module === $module['module'] ? 'active' : ''
                    ));
                }

            }
        ));
    }
}

Answer 1

<?php
echo is_callable($navigation) ? call_user_func($navigation) : $navigation;
?>