Sha256: fbbcb6173cc76fb6a5ef1495e22697a7de3b285d392d7ce39b2978093717c129
Contents?: true
Size: 1.35 KB
Versions: 396
Compression:
Stored size: 1.35 KB
Contents
module Meetup (Weekday(..), Schedule(..), meetupDay) where
import Data.Time.Calendar (Day, addDays, fromGregorian, addGregorianMonthsClip)
import Data.Time.Calendar.WeekDate (toWeekDate)
data Weekday = Monday
| Tuesday
| Wednesday
| Thursday
| Friday
| Saturday
| Sunday
deriving (Enum)
data Schedule = First
| Second
| Third
| Fourth
| Last
| Teenth
deriving (Enum)
type Year = Integer
type Month = Int
addWeeks :: Int -> Day -> Day
addWeeks = addDays . (7 *) . fromIntegral
weekdayNum :: Weekday -> Int
weekdayNum = succ . fromEnum
toWeekday :: Weekday -> Day -> Day
toWeekday w d = fromIntegral offset `addDays` d
where offset | wnum >= wd = wnum - wd
| otherwise = 7 + wnum - wd
wnum = weekdayNum w
(_, _, wd) = toWeekDate d
meetupDay :: Schedule -> Weekday -> Year -> Month -> Day
meetupDay schedule weekday year month =
case schedule of
Last -> (-1) `addWeeks` calcDay nextMonthStart
Teenth -> calcDay $ 12 `addDays` monthStart
enum -> fromEnum enum `addWeeks` firstDay
where
calcDay = toWeekday weekday
monthStart = fromGregorian year month 1
nextMonthStart = addGregorianMonthsClip 1 monthStart
firstDay = calcDay monthStart
Version data entries
396 entries across 396 versions & 1 rubygems