Calendrical.Buddhist (Calendrical v0.3.0)

Implementation of the Thai Buddhist (Buddhist Era) calendar.

The Buddhist calendar shares its month and day structure with the proleptic Gregorian calendar exactly. The only difference is the year numbering: years are counted from the death (parinirvana) of Gautama Buddha, traditionally placed at 543 BCE in the Gregorian calendar. The relation is:

buddhist_year = gregorian_year + 543

So 1 BE corresponds to proleptic Gregorian year −542 (543 BCE in the historical "no year zero" convention) and modern Gregorian 2026 CE corresponds to 2569 BE.

This calendar is the official solar calendar of Thailand, where it is used alongside the Gregorian calendar in everyday life.

Month and day structure

Months and days are identical to Calendrical.Gregorian. Leap years follow the proleptic Gregorian rule:

A year is a leap year if it is divisible by 4, except for centurial years that are not divisible by 400.

Day boundaries are at midnight, matching the Thai civil convention.

Reference

CLDR :buddhist calendar type. The CLDR era data places 1 BE (:be) at proleptic Gregorian −542-01-01.
This module follows Reingold & Dershowitz's Calendrical Calculations (4th ed.) practice of treating year-shifted Gregorian variants as a thin wrapper around the Gregorian implementation.

Summary

Types

day()

month()

year()

Functions

buddhist_year(gregorian_year)

Returns the Buddhist year corresponding to the given Gregorian year.

calendar_base()

Identifies whether this calendar is month or week based.

calendar_year(year, month, day)

Returns the calendar year as displayed on rendered calendars.

cldr_calendar_type()

Defines the CLDR calendar type for this calendar.

cyclic_year(year, month, day)

Returns the cyclic year as displayed on rendered calendars.

date_from_iso_days(iso_days)

Returns a Buddhist {year, month, day} for the given ISO day number.

date_to_iso_days(year, month, day)

Returns the number of ISO days for the given Buddhist year, month, and day.

day_of_era(year, month, day)

Calculates the day and era from the given year, month, and day.

day_of_year(year, month, day)

Calculates the day of the year from the given year, month, and day.

days_in_month(month)

Returns how many days there are in the given month.

days_in_month(year, month)

Returns the number of days in the given Buddhist year and month.

days_in_week()

Returns the number days in a a week.

days_in_year(year)

Returns the number of days in the given Buddhist year (365 or 366).

epoch()

epoch_day_of_week()

extended_year(year, month, day)

Returns the extended year as displayed on rendered calendars.

first_day_of_week()

gregorian_offset()

Returns the offset (in years) between the Buddhist Era and the proleptic Gregorian calendar. buddhist_year - gregorian_offset() yields the corresponding Gregorian year.

gregorian_year(buddhist_year)

Returns the Gregorian year corresponding to the given Buddhist year.

iso_week_of_year(year, month, day)

Calculates the ISO week of the year from the given year, month, and day.

last_day_of_week()

leap_year?(year)

Returns whether the given Buddhist year is a leap year. The underlying calendar is proleptic Gregorian, so the leap-year rule applies to the corresponding Gregorian year.

month(year, month)

Returns a Date.Range.t/0 representing a given month of a year.

month_of_year(year, month, day)

Returns the month of the year from the given year, month, and day.

months_in_leap_year()

Returns the number of months in a leap year.

months_in_ordinary_year()

Returns the number of months in a normal year.

months_in_year(year)

Returns the number of months in a given year.

naive_datetime_from_iso_days(arg)

Converts the t:Calendar.iso_days format to the datetime format specified by this calendar.

naive_datetime_to_iso_days(year, month, day, hour, minute, second, microsecond)

Returns the t:Calendar.iso_days format of the specified date.

periods_in_year(year)

Returns the number of periods in a given year. A period corresponds to a month in month-based calendars and a week in week-based calendars.

plus(year, month, day, date_part, increment, options \\ [])

Adds an increment number of date_parts to a year-month-day.

quarter(year, quarter)

Returns a Date.Range.t/0 representing a given quarter of a year.

quarter_of_year(year, month, day)

Returns the quarter of the year from the given year, month, and day.

Returns the related gregorain year as displayed on rendered calendars.

valid_date?(year, month, day)

Determines if the given year, month, and day form a valid Buddhist date.

week(year, week)

Returns a Date.Range.t/0 representing a given week of a year.

week_of_month(year, month, day)

Calculates the week of the year from the given year, month, and day.

week_of_year(year, month, day)

Calculates the week of the year from the given year, month, and day.

weeks_in_year(year)

Returns the number of weeks in a given year.

year(year)

Returns a Date.Range.t/0 representing a given year.

year_of_era(year)

Calculates the year and era from the given year.

year_of_era(year, month, day)

Calculates the year and era from the given date.

Types

day()

@type day() :: 1..31

month()

@type month() :: 1..12

year()

@type year() :: integer()

Functions

buddhist_year(gregorian_year)

@spec buddhist_year(integer()) :: year()

Returns the Buddhist year corresponding to the given Gregorian year.

calendar_base()

Identifies whether this calendar is month or week based.

calendar_year(year, month, day)

@spec calendar_year(Calendar.year(), Calendar.month(), Calendar.day()) ::
  Calendar.year()

Returns the calendar year as displayed on rendered calendars.

cldr_calendar_type()

Defines the CLDR calendar type for this calendar.

This type is used in support of Calendrical. localize/3.

cyclic_year(year, month, day)

@spec cyclic_year(Calendar.year(), Calendar.month(), Calendar.day()) ::
  Calendar.year()

Returns the cyclic year as displayed on rendered calendars.

date_from_iso_days(iso_days)

@spec date_from_iso_days(integer()) :: {year(), month(), day()}

Returns a Buddhist {year, month, day} for the given ISO day number.

date_to_iso_days(year, month, day)

@spec date_to_iso_days(year(), month(), day()) :: integer()

Returns the number of ISO days for the given Buddhist year, month, and day.

day_of_era(year, month, day)

@spec day_of_era(Calendar.year(), Calendar.month(), Calendar.day()) ::
  {day :: Calendar.day(), era :: Calendar.era()}

Calculates the day and era from the given year, month, and day.

By default we consider on two eras: before the epoch and on-or-after the epoch.

day_of_year(year, month, day)

@spec day_of_year(Calendar.year(), Calendar.month(), Calendar.day()) :: Calendar.day()

Calculates the day of the year from the given year, month, and day.

days_in_month(month)

@spec days_in_month(Calendar.month()) ::
  Calendar.month()
  | {:ambiguous, Range.t() | [pos_integer()]}
  | {:error, :undefined}

Returns how many days there are in the given month.

Must be implemented in derived calendars because we cannot know what the calendar format is.

days_in_month(year, month)

@spec days_in_month(Calendar.year(), Calendar.month()) :: Calendar.month()

@spec days_in_month(year(), month()) :: 28..31

Returns the number of days in the given Buddhist year and month.

days_in_week()

Returns the number days in a a week.

days_in_year(year)

Returns the number of days in the given Buddhist year (365 or 366).

epoch()

epoch_day_of_week()

extended_year(year, month, day)

@spec extended_year(Calendar.year(), Calendar.month(), Calendar.day()) ::
  Calendar.year()

Returns the extended year as displayed on rendered calendars.

first_day_of_week()

gregorian_offset()

@spec gregorian_offset() :: 543

Returns the offset (in years) between the Buddhist Era and the proleptic Gregorian calendar. buddhist_year - gregorian_offset() yields the corresponding Gregorian year.

gregorian_year(buddhist_year)

@spec gregorian_year(year()) :: integer()

Returns the Gregorian year corresponding to the given Buddhist year.

iso_week_of_year(year, month, day)

@spec iso_week_of_year(Calendar.year(), Calendar.month(), Calendar.day()) ::
  {:error, :not_defined}

Calculates the ISO week of the year from the given year, month, and day.

By default this function always returns {:error, :not_defined}.

last_day_of_week()

leap_year?(year)

@spec leap_year?(year()) :: boolean()

Returns whether the given Buddhist year is a leap year. The underlying calendar is proleptic Gregorian, so the leap-year rule applies to the corresponding Gregorian year.

month(year, month)

Returns a Date.Range.t/0 representing a given month of a year.

month_of_year(year, month, day)

@spec month_of_year(Calendar.year(), Calendar.month(), Calendar.day()) ::
  Calendar.month() | {Calendar.month(), Calendrical.leap_month?()}

Returns the month of the year from the given year, month, and day.

months_in_leap_year()

Returns the number of months in a leap year.

months_in_ordinary_year()

Returns the number of months in a normal year.

months_in_year(year)

Returns the number of months in a given year.

naive_datetime_from_iso_days(arg)

@spec naive_datetime_from_iso_days(Calendar.iso_days()) ::
  {Calendar.year(), Calendar.month(), Calendar.day(), Calendar.hour(),
   Calendar.minute(), Calendar.second(), Calendar.microsecond()}

Converts the t:Calendar.iso_days format to the datetime format specified by this calendar.

naive_datetime_to_iso_days(year, month, day, hour, minute, second, microsecond)

@spec naive_datetime_to_iso_days(
  Calendar.year(),
  Calendar.month(),
  Calendar.day(),
  Calendar.hour(),
  Calendar.minute(),
  Calendar.second(),
  Calendar.microsecond()
) :: Calendar.iso_days()

Returns the t:Calendar.iso_days format of the specified date.

periods_in_year(year)

Returns the number of periods in a given year. A period corresponds to a month in month-based calendars and a week in week-based calendars.

plus(year, month, day, date_part, increment, options \\ [])

Adds an increment number of date_parts to a year-month-day.

date_part can be :months only.

quarter(year, quarter)

Returns a Date.Range.t/0 representing a given quarter of a year.

quarter_of_year(year, month, day)

@spec quarter_of_year(Calendar.year(), Calendar.month(), Calendar.day()) ::
  Calendrical.quarter()

Returns the quarter of the year from the given year, month, and day.

related_gregorian_year(year, month, day)

@spec related_gregorian_year(Calendar.year(), Calendar.month(), Calendar.day()) ::
  Calendar.year()

Returns the related gregorain year as displayed on rendered calendars.

valid_date?(year, month, day)

Determines if the given year, month, and day form a valid Buddhist date.

week(year, week)

Returns a Date.Range.t/0 representing a given week of a year.

week_of_month(year, month, day)

@spec week_of_month(Calendar.year(), Calendar.month(), Calendar.day()) ::
  {pos_integer(), pos_integer()} | {:error, :not_defined}

Calculates the week of the year from the given year, month, and day.

By default this function always returns {:error, :not_defined}.

week_of_year(year, month, day)

@spec week_of_year(Calendar.year(), Calendar.month(), Calendar.day()) ::
  {:error, :not_defined}

Calculates the week of the year from the given year, month, and day.

By default this function always returns {:error, :not_defined}.

weeks_in_year(year)

Returns the number of weeks in a given year.

year(year)

Returns a Date.Range.t/0 representing a given year.

year_of_era(year)

@spec year_of_era(Calendar.year()) :: {year :: Calendar.year(), era :: Calendar.era()}

Calculates the year and era from the given year.

year_of_era(year, month, day)

@spec year_of_era(Calendar.year(), Calendar.month(), Calendar.day()) ::
  {year :: Calendar.year(), era :: Calendar.era()}

Calculates the year and era from the given date.