> BTW, what did you think of the idea of using recutils format as the
> output?  (Either as the sole output format, or otherwise as a secondary
> format.)

I like the idea.  It’s always better to use a documented format,
especially when it comes with a mode for Emacs.  And don’t forget that
‘--search’ already uses recutils.  I didn’t say anything before because
I haven’t tried to implement this part yet.

>> Do you see any problems?  Please check everything (especially the
>> ‘first-month’ and ‘last-month’ functions).

> Better yet: write test cases.  :-)

I have some tests, but you have to modify ‘int’ and the other related
procedures to use them.  So it’s not an option.

I’m also not sure what’s the best way to test the ‘first-month’ and
‘last-month’ functions (the validation part).  Any ideas?

> The code otherwise looks OK, but disentangling parsing from validation
> will make it even more pleasant IMO.

I agree.  I just haven’t found a way that avoids unnecessary repetition.

(I’ll comment on other issues later.)

Could you share your thoughts on other things that are marked with
“XXX”?