Hot on the heels of the 0.1 release of time-recurrence: http://hackage.haskell.org/package/time-recurrence comes your favorite recurring time library: time-recurrence-0.2. At this point the library can generate many of the examples given in section 3.8.5.3 of the iCalendar RFC. The interface has been reworked to make things more concise, an example:
-- Generate every 10 days, 5 occurrences startDate = utcGregorianWithTime 1997 9 2 14 0 0 -- Y M D HH MM SS map moment $ take 5 $ recurBy 10 [] $ Daily startDate [1997-09-02 14:00:00 UTC ,1997-09-12 14:00:00 UTC ,1997-09-22 14:00:00 UTC ,1997-10-02 14:00:00 UTC ,1997-10-12 14:00:00 UTC]
I'm still tweaking the main data structures so things are very unstable right now. There is no support for operators like the iCalendar BYSETPOS, which would allow you to generate "the 30th of the month in June if it is a Week Day otherwise the last Week Day in June". For the future I also am looking at how to enforce some of the more esoteric iCalendar rules, such as using BYMONTHDAY in a MONTHLY frequency when also using BYDAY. Since I am not being strict I can simply punt on the matter, but it would be interesting to support such dependencies. As always I encourage all feedback, suggestions and pull requests. -Chris