example\MaybeMonadAndCollectionTest::test_it_should_extract_elements_which_exists PHP Метод

    public function test_it_should_extract_elements_which_exists($data)
    {
        // $get :: String a -> [b] -> Maybe b
        $get = f\curryN(2, function ($key, $array) {
            return isset($array[$key]) ? m\just($array[$key]) : m\nothing();
        });
        $listOfFirstImages = f\pipeline(Listt::of, f\map(m\maybeNull), f\bind(f\bind($get('meta'))), f\bind(f\bind($get('images'))), f\bind(f\bind($get(0))), f\join);
        $result = $listOfFirstImages($data);
        $this->assertEquals(Listt::of([m\just('//first.jpg'), m\just('//third.jpg'), m\nothing()]), $result);
    }