This is a great module. The comment on performance and Perl is well placed. This module will not be slowing down your code any more than the Perl interpreter itself.
One useful additional feature that this module would benefit from would be
- given a date, what week of the month is it on? for example, Jun 13th 2001 lies in the 3rd week of June 2001.
- given a date, what is the ordinal of its day of the week in the month? for example, Jun 13th 2001 is the 2nd wednesday of June 2001
- given two dates, calculate the difference in business days. for example, (Jun 13th 2001)-(Jun 8th 2001) = 3 business days
- likewise, add n business days to any date
- better support for unix timestamps (epoch time) values
However, these can be fairly easily implemented within the framework of the module. I