public static function getPrimitives() {
        return [
            Type::TYPE_NULL     => 'null',
            Type::TYPE_BOOLEAN  => 'bool',
            Type::TYPE_LONG     => 'int',
            Type::TYPE_DOUBLE   => 'float',
            Type::TYPE_STRING   => 'string',
            Type::TYPE_OBJECT   => 'object',
            Type::TYPE_ARRAY    => 'array',
            Type::TYPE_CALLABLE => 'callable',
        ];
    }