Data.Thyme.Calendar

A calendar-agnostic day, internally represented as a count of days since 1858-11-17, the Modified Julian Day (MJD) epoch.

To convert a Day to the corresponding YearMonthDay in the Gregorian calendar, see gregorian.

> gregorian # YearMonthDay 2016 3 1
2016-03-01

Day is an instance of AffineSpace where Diff Day = Days, so arithmetic on Day and Days can be performed with the .-., .+^, and .-^ operators.

> gregorian # YearMonthDay 2016 3 1  .-.  gregorian # YearMonthDay 2016 2 1
29

> gregorian # YearMonthDay 2016 3 1 .-^ 1
2016-02-29

Other ways of viewing a Day include ordinalDate, and weekDate.

Convert between a Day and the corresponding count of days from 1858-11-17, the MJD epoch.

modifiedJulianDay = iso toModifiedJulianDay ModifiedJulianDay

> modifiedJulianDay # 0
1858-11-17
> gregorian # YearMonthDay 2016 3 1 & modifiedJulianDay %~ subtract 1
2016-02-29

Calendar year.

Calendar month. January = 1

Calendar day-of-month, starting from 1.

A strict triple of a Year, a Day, and a Month.

A duration/count of years.

A duration/count of months.

A duration/count of days.

Is it a leap year according to the Gregorian calendar?

Conversion between a Gregorian OrdinalDate and the corresponding YearMonthDay.

> OrdinalDate 2016 32 ^. yearMonthDay
YearMonthDay {ymdYear = 2016, ymdMonth = 2, ymdDay = 1}

> yearMonthDay # YearMonthDay 2016 2 1
OrdinalDate {odYear = 2016, odDay = 32}

Conversion between a Day and its YearMonthDay.

gregorian = ordinalDate . yearMonthDay

> ModifiedJulianDay 0 ^. gregorian
YearMonthDay {ymdYear = 1858, ymdMonth = 11, ymdDay = 17}

> gregorian # YearMonthDay 1858 11 17
1858-11-17

Conversion between a YearMonthDay and the corresponding Day. Returns Nothing for invalid input.

> gregorianValid (YearMonthDay 2015 2 28)
Just 2015-02-28

> gregorianValid (YearMonthDay 2015 2 29)
Nothing

Shows a Day in ISO 8601 YYYY-MM-DD format.

See Data.Thyme.Format for other possibilities.

Add some Days to a calendar Day to get a new Day.

addDays = flip (.+^)
addDays n d ≡ d .+^ n

See also the AffineSpace instance for Day.

Add some number of Months to the given Day; if the original DayOfMonth exceeds that of the new Month, it will be clipped to the last day of the new Month.

addGregorianMonthsClip n = gregorian %~ gregorianMonthsClip n

Add some number of Months to the given Day; if the original DayOfMonth exceeds that of the new Month, it will be rolled over into the following Month.

addGregorianMonthsRollover n = gregorian %~ gregorianMonthsRollover n

Add some number of Years to the given Day, with February 29th clipped to February 28th if necessary.

addGregorianYearsClip n = gregorian %~ gregorianYearsClip n

Add some number of Years to the given Day, with February 29th rolled over to March 1st if necessary.

addGregorianYearsRollover n = gregorian %~ gregorianYearsRollover n

Subtract two calendar Days for the difference in Days.

diffDays = (.-.)
diffDays a b = a .-. b

See also the AffineSpace instance for Day.

Construct a Day from a Gregorian calendar date. Does not validate the input.

fromGregorian y m d = gregorian # YearMonthDay y m d

Construct a Day from a Gregorian calendar date. Returns Nothing for invalid input.

fromGregorianValid y m d = gregorianValid (YearMonthDay y m d)

The number of days in a given month in the Gregorian calendar.

> gregorianMonthLength 2005 2
28

Add months, with days past the last day of the month clipped to the last day.

See also addGregorianMonthsClip.

> gregorianMonthsClip 1 $ YearMonthDay 2005 1 30
YearMonthDay {ymdYear = 2005, ymdMonth = 2, ymdDay = 28}

Add months, with days past the last day of the month rolling over to the next month.

See also addGregorianMonthsRollover.

> gregorianMonthsRollover 1 $ YearMonthDay 2005 1 30
YearMonthDay {ymdYear = 2005, ymdMonth = 3, ymdDay = 2}

Add years, matching month and day, with February 29th clipped to the 28th if necessary.

See also addGregorianYearsClip.

> gregorianYearsClip 2 $ YearMonthDay 2004 2 29
YearMonthDay {ymdYear = 2006, ymdMonth = 2, ymdDay = 28}

Add years, matching month and day, with February 29th rolled over to March 1st if necessary.

See also addGregorianYearsRollover.

> gregorianYearsRollover 2 $ YearMonthDay 2004 2 29
YearMonthDay {ymdYear = 2006, ymdMonth = 3, ymdDay = 1}

Convert a Day to its Gregorian Year, Month, and DayOfMonth.

toGregorian (view gregorian -> YearMonthDay y m d) = (y, m, d)