Module Calendar_sig.S.Date

module Date: Date_sig.S 

Date implementation used by this calendar.


Datatypes

type field = Period.date_field 

The different fields of a date.

type -[< field ] date 

Type of a date, without specifying any precision level.

type t = field date 

Type of a date.

type day = 
| Sun
| Mon
| Tue
| Wed
| Thu
| Fri
| Sat

Days of the week.

type month = 
| Jan
| Feb
| Mar
| Apr
| May
| Jun
| Jul
| Aug
| Sep
| Oct
| Nov
| Dec

Months of the year.

type year = int 

Year as an int.

Exceptions

exception Out_of_bounds

Raised when a date is outside the Julian period.

exception Undefined

Raised when a date belongs to [October 5th, 1582; October 14th, 1582].

Constructors

val make : year -> int -> int -> t

make year month day makes the date year-month-day. A BC year y corresponds to the year -(y+1).

val lmake : year:year -> ?month:int -> ?day:int -> unit -> t

Labelled version of make. The default value of month and day is 1.

val make_year : int -> [< `Year ] date

make_year y makes a date only represented by its year y. The month and the day of such a date are not relevant.

val make_year_month : int -> int -> [< `Month | `Year ] date

make_year_month y m makes a date only represented by its year y and its month m. The day of such a date is not relevant.

val today : unit -> t

Date of the current day (based on Time_Zone.current ()).

val from_jd : int -> t

Make a date from its Julian day.

val from_mjd : int -> t

Make a date from its modified Julian day (i.e. Julian day - 2 400 001). The Modified Julian day is more manageable than the Julian day.

val from_day_of_year : year -> int -> t

Make a date from a year and its day of the year.

Getters

val days_in_month : [< field > `Month `Year ] date -> int

Number of days in the month of a date.

val day_of_week : t -> day

Day of the week.

val day_of_month : t -> int

Day of the month.

val day_of_year : t -> int

Day of the year.

val week : t -> int

Week.

val month : [< field > `Month ] date -> month

Month.

val year : [< field > `Year ] date -> year

Year.

val to_jd : t -> int

Julian day.

val to_mjd : t -> int

Modified Julian day (i.e. Julian day - 2 400 001). The Modified Julian day is more manageable than the Julian day.

Dates are comparable

val equal : [< field ] date -> [< field ] date -> bool

Equality function between two dates.

val compare : [< field ] date -> [< field ] date -> int

Comparison function between two dates.

val hash : [< field ] date -> int

Hash function for dates.

Boolean operations on dates

val is_valid_date : year -> int -> int -> bool

Check if a date is valid, that is the date has not been coerced to look like a real date.

val is_leap_day : t -> bool

Return true if a date is a leap day (i.e. February, 24th of a leap year); false otherwise.

val is_gregorian : t -> bool

Return true if a date belongs to the Gregorian calendar; false otherwise.

val is_julian : t -> bool

Return true iff a date belongs to the Julian calendar; false otherwise.

Coercions

val to_unixtm : t -> Unix.tm

Convert a date into the Unix.tm type. The field is_isdst is always false. The fields Unix.tm_sec, Unix.tm_min and Unix.tm_hour are irrelevant.

val from_unixtm : Unix.tm -> t

Inverse of to_unixtm. Assume the current time zone.

val to_unixfloat : t -> float

Convert a date to a float such than to_unixfloat (make 1970 1 1) returns 0.0. So such a float is convertible with those of the Unix module. The fractional part of the result is always 0.

val from_unixfloat : float -> t

Inverse of to_unixfloat. Ignore the fractional part of the argument. Assume the current time zone.

val to_business : t -> year * int * day

Return the "business week" and the day in this week respecting ISO 8601. Notice that business weeks at the beginning and end of the year can sometimes have year numbers which don't match the real year.

val from_business : year -> int -> day -> t

Inverse of to_business respecting ISO-8601. Notice that business weeks at the beginning and end of the year can sometimes have year numbers which don't match the real year.

val int_of_day : day -> int

Convert a day to an integer respecting ISO-8601. So, Monday is 1, Tuesday is 2, ..., and sunday is 7.

val day_of_int : int -> day

Inverse of int_of_day.

val int_of_month : month -> int

Convert a month to an integer respecting ISO-8601. So, January is 1, February is 2 and so on.

val month_of_int : int -> month

Inverse of int_of_month.

Period

module Period: sig .. end

A period is the number of days between two dates.

Arithmetic operations on dates and periods

val add : ([< field ] as 'a) date ->
'a Period.period -> 'a date

add d p returns d + p.

val sub : ([< field ] as 'a) date ->
'a date ->
[< field > `Day `Week ] Period.period

sub d1 d2 returns the period between d1 and d2.

val precise_sub : ([< field ] as 'a) date ->
'a date -> Period.t

precise_sub d1 d2 returns the period between d1 and d2. It is equivalent to sub, but:

val rem : ([< field ] as 'a) date ->
'a Period.period -> 'a date

rem d p is equivalent to add d (Period.opp p).

val next : ([< field ] as 'a) date -> 'a -> 'a date

next d f returns the date corresponding to the next specified field.

val prev : ([< field ] as 'a) date -> 'a -> 'a date

prev d f returns the date corresponding to the previous specified field.

Operations on years

val is_leap_year : year -> bool

Return true if a year is a leap year; false otherwise.

val same_calendar : year -> year -> bool

Return true if two years have the same calendar; false otherwise.

val days_in_year : ?month:month -> year -> int

Number of days in a year.

days_in_year ~month y returns the number of days in the year y up to the end of the given month. Thus days_in_year ~month:Dec y is the same as days_in_year y.

val weeks_in_year : year -> int

Number of weeks in a year.

val week_first_last : int -> year -> t * t

Return the first and last days of a week in a year.

val nth_weekday_of_month : year -> month -> day -> int -> t

nth_weekday_of_month y m d n returns the n-th day d in the month m of the year y (for instance the 3rd Thursday of the month).

val century : year -> int

Century of a year.

val millenium : year -> int

Millenium of a year.

val solar_number : year -> int

Solar number.

In the Julian calendar there is a one-to-one relationship between the Solar number and the day on which a particular date falls.

val indiction : year -> int

Indiction.

The Indiction was used in the middle ages to specify the position of a year in a 15 year taxation cycle. It was introduced by emperor Constantine the Great on 1 September 312 and ceased to be used in 1806.

The Indiction has no astronomical significance.

val golden_number : year -> int

Golden number.

Considering that the relationship between the moon's phases and the days of the year repeats itself every 19 years, it is natural to associate a number between 1 and 19 with each year. This number is the so-called Golden number.

val epact : year -> int

Epact.

The Epact is a measure of the age of the moon (i.e. the number of days that have passed since an "official" new moon) on a particular date.

val easter : year -> t

Easter Sunday.

In the Christian world, Easter (and the days immediately preceding it) is the celebration of the death and resurrection of Jesus in (approximately) AD 30.

val carnaval : year -> t

Carnaval Monday. carnaval y is easter y - 48.

val mardi_gras : year -> t

Mardi Gras. mardi_gras y is easter y - 47.

val ash : year -> t

Ash Wednesday. ash y is easter y - 46.

val palm : year -> t

Palm Sunday. palm y is easter y - 7.

val easter_friday : year -> t

Easter Friday. easter_friday y is easter y - 2.

val easter_saturday : year -> t

Easter Saturday. easter_saturday y is easter y - 1.

val easter_monday : year -> t

Easter Monday. easter_monday y is easter y + 1.

val ascension : year -> t

Ascension. ascension y is easter y + 39.

val withsunday : year -> t

Withsunday. withsunday y is easter y + 49.

val withmonday : year -> t

Withmonday. withmonday y is easter y + 50.

val corpus_christi : year -> t

Feast of Corpus Christi. corpus_christi y is easter + 60.