@hackage time-recurrence0.6

time-recurrence is a Haskell library for working with recurring date/times.

The iCalendar Specifcation (RFC 5545) is used for inspiration of this library, however the library does not make an effort to track the RFC at all times. A future Data.Time.Recurrence.RFC5545 library would be a useful add-on for those in need of strict RFC compliance.

Examples:

parse822Time :: String -> UTCTime parse822Time = ...

nov1996 = parse822Time "Tue, 05 Nov 1996 09:00:00 -0400" mar1997 = parse822Time "Mon, 10 Mar 1997 09:00:00 -0400" sep1997 = parse822Time "Tue, 02 Sep 1997 09:00:00 -0400" oct1997 = parse822Time "Fri, 10 Oct 1997 00:00:00 -0400" dec1997 = parse822Time "Wed, 24 Dec 1997 00:00:00 -0400" jan1998 = parse822Time "Thu, 01 Jan 1998 09:00:00 -0400" jan2000 = parse822Time "Mon, 31 Jan 2000 09:00:00 -0400"

Daily for 10 occurrences:

take 10 $ recur daily begin sep1997

Daily until Dec. 24, 1997:

takeWhile (<= dec1997) $ recur daily begin sep1997

Every other day - forever:

recur daily by 2 begin sep1997

Every 10 days, 5 occurrences:

take 5 $ recur daily by 10 begin sep1997

Every day in January, for 3 years:

takeWhile (<= jan2000) $ recur yearly starting jan1998 $ enumMonths [January] >=> filterWeekDays [Monday .. Sunday]

takeWhile (<= jan2000) $ recur daily starting jan1998 $ enumMonths [January]

Weekly for 10 occurrences:

take 10 $ recur weekly begin sep1997

Weekly until Dec. 24, 1997:

takeWhile (<= dec1997) $ recur weekly withStartOfWeek Sunday begin sep1997

Every other week - forever:

recur weekly by 2 begin sep1997

Weekly on Tuesday and Thursday for five weeks:

takeUntil (<= oct1997) $ recur weekly withStartOfWeek Sunday starting sep1997 $ enumWeekDaysInWeek [Tuesday, Thursday]

or

take 10 $ recur weekly withStartOfWeek Sunday starting sep1997 $ enumWeekDaysInWeek [Tuesday, Thursday]

Every other week (Monday, Wednesday, Firday) until Dec. 24, 1997:

takeWhile (<= dec1997) $ recur weekly withStartOfWeek Sunday by 2 starting sep1997$ enumWeekDaysInWeek [Monday, Wednesday, Friday] >=>

Every other week on Tuesday and Thursday, for 8 occurrences:

take 8 $ recur weekly withStartOfWeek Sunday by 2 starting sep1997 $ enumWeekDaysInWeek [Tuesday, Thursday]

Monthly on the first Friday for 10 occurrences:

take 10 $ recur monthly starting sep1997 $ enumWeekDaysInMonth [Friday] >=> nthWeekDayOfMonth [1]

Monthly on the first Friday until Dec. 24, 1997

takeWhile (<= dec1997) $ recur monthly starting sep1997 $ enumWeekDaysInMonth [Friday] >=> nthWeekDayOfMonth [1]

Every other month on the first and last Sunday of the month for 10 occurrences:

take 10 $ recur monthly by 2 starting sep1997 $ enumWeekDaysInMonth [Sunday] >=> nthWeekDayOfMonth [1,-1]

Monthly on the second-to-last Monday of the month for 6 months:

take 6 $ recur monthly starting sep1997 $ enumWeekDaysInMonth [Monday] >=> nthWeekDayOfMonth [-2]

Monthly on the third-to-last day of the month, forever:

recur monthly starting sep1997 $ enumDays [-3]

Monthly on the 2nd and 15th of the month for 10 occurrences:

take 10 $ recur monthly starting sep1997 $ enumDays [2,15]

Monthly on the first and last day of the month for 10 occurrences:

take 10 $ recur monthly starting sep1997 $ enumDays [1,-1]

Every 18 months on the 10th thru 15th of the month for 10 occurrences:

take 10 $ recur monthly by 18 starting sep1997 $ enumDays [10 .. 15]

Every Tuesday, every other month:

recur monthly by 2 starting sep1997 $ enumWeekDaysInMonth [Tuesday]

Yearly in June and July for 10 occurrences:

take 10 $ recur yearly starting sep1997 $ enumMonths [June, July]

Every other year on January thru March for 10 occurrences:

take 10 $ recur yearly by 2 starting mar1997 $ enumMonths [January .. March] >=> enumWeekDaysInMonth [Monday .. Sunday]

Every third year on the 1st, 100th, and 200th day for 10 occurrences:

take 10 $ recur yearly by 3 starting sep1997 $ enumYearDays [1,100,200]

Every 20th Monday of the year, forever:

recur monthly starting sep1997 $ enumWeekDaysInMonth [Monday] >=> nthWeekDay [20]

Monday of week number 20, forever:

recur yearly starting mar1997 $ enumWeekNumbers [20] >=> filterWeekDays [Monday]

or

recur weekly starting mar1997 $ filterWeekNumbers [20] >=> filterWeekDays [Monday]

Every Thursday in March, forever:

recur yearly starting mar1997 $ enumMonths [March] >=> enumWeekDaysInMonth [Thrusday]

Every Thursday, but only during June thru August, forever:

recur yearly starting mar1997 $ enumMonths [June .. August] >=> enumWeekDaysInMonth [Thursday]

Firday the 13th, Forever:

recur monthly starting sep1997 $ enumDays [13] >=> filterWeekDays [Friday]

The first Saturday that follows the first Sunday of the month, forever:

recur monthly sep1997 $ enumDays [7 .. 13] >=> filterWeekDays [Saturday]

U.S. Presidential Election Day: Every 4 years, the first Tuesday after a Monday in November, forever:

recur yearly by 4 starting nov1996 $ enumMonths [November] >=> enumDays [2 .. 8] >=> filterWeekDays [Tuesday]

The third instance into the month of one of Tuesday, Wednesday, or Thursday, for the next 3 months.

take 3 $ recur monthly starting sep1997 $ enumWeekDaysInMonth [Tuesday .. Thursday] >=> nthWeekDayOfMonth [3]

The second-to-last weekday of the month:

recur monthly starting sep1997 $ enumWeekDaysOfMonth [Monday .. Friday] >=> nthWeekDayOfMonth [-2]

Every 3 hours from 9:00 AM to 5:00 PM on a specific day:

takeWhile (<= addSeconds sep1997 (8 * oneHour)) $ recur hourly by 3 begin sep1997

Every 15 minutes for 6 occurrences:

take 6 $ recur minutely by 15 begin sep1997

Every hour and a hald for 4 occurrences:

take 4 $ recur minutely by 90 begin sep1997

Every 20 minutes from 9:00 AM to 4:40 PM every day:

recur daily starting sep1997 $ enumHours [9 .. 16] >=> enumMinutes [0,20,40]

or

recur minutely by 20 starting sep1997 $ enumHours [9 .. 16]

The following two examples will generate different results due to changes in the start of the week.

take 4 $ recur weekly by 2 withStartOfWeek Monday $ enumWeekDaysInWeek [Tuesday,Sunday]

vs

take 4 $ recur weekly by 2 withStartOfWeek Sunday $ enumWeekDaysInWeek [Tuesday,Sunday]

An example where an invalid date (Feb. 30) is ignored:

take 5 $ recur monthly starting jan2000 $ enumDays [15,30]

The 15th and the 30th of the month, forever:

recur monthly starting sep1997 $ enumDays [15,30]

The 15th and the 30th of the month, but only during the work week:

recur monthly starting sep1997 $ enumDays [15,30] >=> filterWeekDays [Monday .. Friday]