Hi,
> I have attached a new patch v2 with following changes:
>
> - Handled invalid cases like 'viv', 'lxl', and 'dcd'.
> - Changed errcode to 22P07 because 22P06 was already taken.
> - Removed TODO.
> - Added a few positive & negative tests.
> - Updated documentation.
>
> Looking forward to your feedback.
While playing with the patch I noticed that to_char(..., 'RN') doesn't
seem to be test-covered. I suggest adding the following test:
```
WITH rows AS (
SELECT i, to_char(i, 'FMRN') AS roman
FROM generate_series(1, 3999) AS i
) SELECT bool_and(to_number(roman, 'RN') = i) FROM rows;
bool_and
----------
t
```
... in order to fix this while on it. The query takes ~12 ms on my laptop.
--
Best regards,
Aleksander Alekseev
