syntax error on zephir

1. My code is ....

    public static function register(key, value, graceful = false)
    {
        var _tmp; let _tmp = self::_registry[key];
        if (isset(_tmp)) {
            if (graceful) {
                return;
            }
            self::throwException("Mage registry key "" . key . "" already exists");
        }
        self::_registry[key] = value;
    }

OR:

    public static function register(key, value, graceful = false)
    {
        if fetch val, self::_registry[key]{
            if (graceful) {
                return;
            }
            self::throwException("Mage registry key "" . key . "" already exists");
        }
        self::_registry[key] = value;
    }

ParseException: Syntax error in /var/www/magento/shell/zephir/dumy/dumy/mage.zep on line 116

             let _tmp = self::_registry[key];
        -------------------------------^

Why is syntax error ?

2. My code is.......

final class Mage
{
    private static _registry = [];
......................
}

ParseException: Syntax error in /var/www/magento/shell/zephir/dumy/dumy/mage.zep on line 10

            private static _registry = [];
        -------------------------------^

why is syntax error ? Is it impossible array init with variable declaration ?