package async

create_exn ~y ~m ~d creates the date specified in the arguments. Arguments are validated, and are not normalized in any way. So, days must be within the limits for the month in question, numbers cannot be negative, years must be fully specified, etc.

For details on this ISO format, see:

http://www.wikipedia.org/wiki/iso8601

YYYYMMDD

MM/DD/YYYY

Only accurate after 1752-09

Week of the year, from 1 to 53, along with the week-numbering year to which the week belongs. The week-numbering year may not correspond to the calendar year in which the provided date occurs.

According to ISO 8601, weeks start on Monday, and the first week of a year is the week that contains the first Thursday of the year. This means that dates near the end of the calendar year can have week number 1 and belong to the following week-numbering year, and dates near the beginning of the calendar year can have week number 52 or 53 and belong to the previous week-numbering year.

The triple (week-numbering year, week number, week day) uniquely identifies a particular date, which is not true if the calendar year is used instead.

See week_number_and_year for the meaning of week number.

Monday through Friday are business days, unless they're a holiday.

add_days t n adds n days to t and returns the resulting date.

Inaccurate when crossing 1752-09.

add_months t n returns date with max days for the month if the date would be invalid. e.g. adding 1 month to Jan 30 results in Feb 28 due to Feb 30 being an invalid date, Feb 29 is returned in cases of leap year.

In particular, this means adding x months and then adding y months isn't the same as adding x + y months, and in particular adding x months and then -x months won't always get you back where you were. *

add_years t n has the same semantics as add_months for adding years to Feb 29 of a leap year, i.e., when the addition results in a date in a non-leap year, the result will be Feb 28 of that year.

diff t1 t2 returns date t1 minus date t2 in days.

diff_weekdays t1 t2 returns the number of weekdays in the half-open interval [t2,t1) if t1 >= t2, and - diff_weekdays t2 t1 otherwise.

diff_weekend_days t1 t2 returns the number of days that are weekend days in the half-open interval [t2,t1) if t1 >= t2, and - diff_weekend_days t2 t1 otherwise.

add_weekdays t 0 returns the next weekday if t is a weekend and t otherwise. Unlike add_days this is done by looping over the count of days to be added (forward or backwards based on the sign), and is O(n) in the number of days to add. Beware, add_weekdays sat 1 or add_weekdays sun 1 both return the next tue, not the next mon. You may want to use following_weekday if you want the next following weekday, following_weekday (fri|sat|sun) would all return the next mon.

add_business_days t ~is_holiday n returns a business day even when n=0. add_business_days ~is_holiday:(fun _ -> false) ... is the same as add_weekdays.

If you don't want to skip Saturday or Sunday, use add_days_skipping.

add_days_skipping t ~skip n adds n days to t, ignoring any date satisfying skip, starting at the first date at or after t that does not satisfy skip. For example, if skip t = true, then add_days_skipping t ~skip 0 > t.

add_business_days and add_weekdays are special cases of add_days_skipping.

the following returns a closed interval (endpoints included)

first_strictly_after t ~on:day_of_week returns the first occurrence of day_of_week strictly after t.

days_in_month ~year ~month returns the number of days in month, using year only if month = Month.Feb to check if there is a leap year.

Incorrect for September 1752.

is_leap_year ~year returns true if year is considered a leap year

The starting date of the UNIX epoch: 1970-01-01

gen_incl d1 d2 generates dates in the range between d1 and d2, inclusive, with the endpoints having higher weight than the rest. Raises if d1 > d2.

gen_uniform_incl d1 d2 generates dates chosen uniformly in the range between d1 and d2, inclusive. Raises if d1 > d2.

Days provides a linear representation of dates that is optimized for arithmetic on the number of days between dates, rather than for representing year/month/day components. This module is intended for use only in performance-sensitive contexts where dates are manipulated more often than they are constructed or deconstructed; most clients should use the ordinary t.