require_once '/path/to/vendor/autoload.php';

$loader = new \Twig\Loader\ArrayLoader([
    'index' => 'Hello {{ name }}!',
]);
$twig = new \Twig\Environment($loader);

echo $twig->render('index', ['name' => 'Fabien']);

$ php test.php
PHP Parse error:  syntax error, unexpected token "->" in /home/john/Desktop/Twig/vendor/twig/twig/src/Extension/AbstractExtension.php on line 44