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{-# LANGUAGE Safe #-}
module Data.Time.Calendar.CalendarDiffDays (
-- * Calendar Duration
module Data.Time.Calendar.CalendarDiffDays,
) where
import Control.DeepSeq
import Data.Data
data CalendarDiffDays = CalendarDiffDays
{ cdMonths :: Integer
, cdDays :: Integer
}
deriving
( Eq
, -- | @since 1.9.2
Data
, -- | @since 1.9.2
Typeable
)
instance NFData CalendarDiffDays where
rnf (CalendarDiffDays m d) = rnf m `seq` rnf d `seq` ()
-- | Additive
instance Semigroup CalendarDiffDays where
CalendarDiffDays m1 d1 <> CalendarDiffDays m2 d2 = CalendarDiffDays (m1 + m2) (d1 + d2)
-- | Additive
instance Monoid CalendarDiffDays where
mempty = CalendarDiffDays 0 0
mappend = (<>)
instance Show CalendarDiffDays where
show (CalendarDiffDays m d) = "P" ++ show m ++ "M" ++ show d ++ "D"
calendarDay :: CalendarDiffDays
calendarDay = CalendarDiffDays 0 1
calendarWeek :: CalendarDiffDays
calendarWeek = CalendarDiffDays 0 7
calendarMonth :: CalendarDiffDays
calendarMonth = CalendarDiffDays 1 0
calendarYear :: CalendarDiffDays
calendarYear = CalendarDiffDays 12 0
-- | Scale by a factor. Note that @scaleCalendarDiffDays (-1)@ will not perfectly invert a duration, due to variable month lengths.
scaleCalendarDiffDays :: Integer -> CalendarDiffDays -> CalendarDiffDays
scaleCalendarDiffDays k (CalendarDiffDays m d) = CalendarDiffDays (k * m) (k * d)
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