function to create a recursable closure

rf.php

<?php
function rf(Closure $f) {
    return new class($f) {
        private $f;
        public function __construct(Closure $f)
        {
            $this->f = $f;
        }

        public function __invoke() {
            return ($this->f->bindTo($this))(...func_get_args());
        }
    };
}