Calendar.ISO

The default calendar implementation, a Gregorian calendar following ISO 8601.

This calendar implements a proleptic Gregorian calendar and is therefore compatible with the calendar used in most countries today. The proleptic means the Gregorian rules for leap years are applied for all time, consequently the dates give different results before the year 1583 from when the Gregorian calendar was adopted.

ISO 8601 compliance

The ISO 8601 specification is feature-rich, but allows applications to selectively implement most parts of it. The choices Elixir makes are catalogued below.

Features

The standard library supports a minimal set of possible ISO 8601 features. Specifically, the parser only supports calendar dates and does not support ordinal and week formats.

By default Elixir only parses extended-formatted date/times. You can opt-in to parse basic-formatted date/times.

NaiveDateTime.to_iso8601/2 and DateTime.to_iso8601/2 allow you to produce either basic or extended formatted strings, and Calendar.strftime/2 allows you to format datetimes however else you desire.

Elixir does not support reduced accuracy formats (for example, a date without the day component) nor decimal precisions in the lowest component (such as 10:01:25,5). No functions exist to parse ISO 8601 durations or time intervals.

Examples

Elixir expects the extended format by default when parsing:

iex> Calendar.ISO.parse_naive_datetime("2015-01-23T23:50:07")
{:ok, {2015, 1, 23, 23, 50, 7, {0, 0}}}
iex> Calendar.ISO.parse_naive_datetime("20150123T235007")
{:error, :invalid_format}

Parsing can be restricted to basic if desired:

iex> Calendar.ISO.parse_naive_datetime("20150123T235007Z", :basic)
{:ok, {2015, 1, 23, 23, 50, 7, {0, 0}}}
iex> Calendar.ISO.parse_naive_datetime("20150123T235007Z", :extended)
{:error, :invalid_format}

Only calendar dates are supported in parsing; ordinal and week dates are not.

iex> Calendar.ISO.parse_date("2015-04-15")
{:ok, {2015, 4, 15}}
iex> Calendar.ISO.parse_date("2015-105")
{:error, :invalid_format}
iex> Calendar.ISO.parse_date("2015-W16")
{:error, :invalid_format}
iex> Calendar.ISO.parse_date("2015-W016-3")
{:error, :invalid_format}

Years, months, days, hours, minutes, and seconds must be fully specified:

iex> Calendar.ISO.parse_date("2015-04-15")
{:ok, {2015, 4, 15}}
iex> Calendar.ISO.parse_date("2015-04")
{:error, :invalid_format}
iex> Calendar.ISO.parse_date("2015")
{:error, :invalid_format}

iex> Calendar.ISO.parse_time("23:50:07.0123456")
{:ok, {23, 50, 7, {12345, 6}}}
iex> Calendar.ISO.parse_time("23:50:07")
{:ok, {23, 50, 7, {0, 0}}}
iex> Calendar.ISO.parse_time("23:50")
{:error, :invalid_format}
iex> Calendar.ISO.parse_time("23")
{:error, :invalid_format}

Extensions

The parser and formatter adopt one ISO 8601 extension: extended year notation.

This allows dates to be prefixed with a + or - sign, extending the range of expressible years from the default (0000..9999) to -9999..9999. Elixir still restricts years in this format to four digits.

Examples

iex> Calendar.ISO.parse_date("-2015-01-23")
{:ok, {-2015, 1, 23}}
iex> Calendar.ISO.parse_date("+2015-01-23")
{:ok, {2015, 1, 23}}

iex> Calendar.ISO.parse_naive_datetime("-2015-01-23 23:50:07")
{:ok, {-2015, 1, 23, 23, 50, 7, {0, 0}}}
iex> Calendar.ISO.parse_naive_datetime("+2015-01-23 23:50:07")
{:ok, {2015, 1, 23, 23, 50, 7, {0, 0}}}

iex> Calendar.ISO.parse_utc_datetime("-2015-01-23 23:50:07Z")
{:ok, {-2015, 1, 23, 23, 50, 7, {0, 0}}, 0}
iex> Calendar.ISO.parse_utc_datetime("+2015-01-23 23:50:07Z")
{:ok, {2015, 1, 23, 23, 50, 7, {0, 0}}, 0}

Additions

ISO 8601 does not allow a whitespace instead of T as a separator between date and times, both when parsing and formatting. This is a common enough representation, Elixir allows it during parsing.

The formatting of dates in NaiveDateTime.to_iso8601/1 and DateTime.to_iso8601/1 do produce specification-compliant string representations using the T separator.

Examples

iex> Calendar.ISO.parse_naive_datetime("2015-01-23 23:50:07.0123456")
{:ok, {2015, 1, 23, 23, 50, 7, {12345, 6}}}
iex> Calendar.ISO.parse_naive_datetime("2015-01-23T23:50:07.0123456")
{:ok, {2015, 1, 23, 23, 50, 7, {12345, 6}}}

iex> Calendar.ISO.parse_utc_datetime("2015-01-23 23:50:07.0123456Z")
{:ok, {2015, 1, 23, 23, 50, 7, {12345, 6}}, 0}
iex> Calendar.ISO.parse_utc_datetime("2015-01-23T23:50:07.0123456Z")
{:ok, {2015, 1, 23, 23, 50, 7, {12345, 6}}, 0}

Summary

Types

bce(): "Before the Current Era" or "Before the Common Era" (BCE), for those years less than 1.
ce(): The "Current Era" or the "Common Era" (CE) which starts in year 1.
day()
day_of_week(): Integer that represents the day of the week, where 1 is Monday and 7 is Sunday.
day_of_year()
era(): The calendar era.
hour()
microsecond(): Microseconds with stored precision.
minute()
month()
quarter_of_year()
second()
weekday()
year()
year_of_era()

Functions

date_to_string(year, month, day, format \\ :extended): Converts the given date into a string.
datetime_to_string(year, month, day, hour, minute, second, microsecond, time_zone, zone_abbr, utc_offset, std_offset, format \\ :extended): Converts the datetime (with time zone) into a string.
day_of_era(year, month, day): Calculates the day and era from the given year, month, and day.
day_of_week(year, month, day, starting_on): Calculates the day of the week 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.
day_rollover_relative_to_midnight_utc(): See Calendar.day_rollover_relative_to_midnight_utc/0 for documentation.
days_in_month(year, month): Returns how many days there are in the given year-month.
leap_year?(year): Returns if the given year is a leap year.
months_in_year(year): Returns how many months there are in the given year.
naive_datetime_from_iso_days(arg): Converts the Calendar.iso_days/0 format to the datetime format specified by this calendar.
naive_datetime_to_iso_days(year, month, day, hour, minute, second, microsecond): Returns the Calendar.iso_days/0 format of the specified date.
naive_datetime_to_string(year, month, day, hour, minute, second, microsecond, format \\ :extended): Converts the datetime (without time zone) into a string.
parse_date(string): Parses a date string in the :extended format.
parse_date(string, format): Parses a date string according to a given format.
parse_naive_datetime(string): Parses a naive datetime string in the :extended format.
parse_naive_datetime(string, format): Parses a naive datetime string according to a given format.
parse_time(string): Parses a time string in the :extended format.
parse_time(string, format): Parses a time string according to a given format.
parse_utc_datetime(string): Parses a UTC datetime string in the :extended format.
parse_utc_datetime(string, format): Parses a UTC datetime string according to a given format.
quarter_of_year(year, month, day): Calculates the quarter of the year from the given year, month, and day.
time_from_day_fraction(arg): Converts a day fraction to this Calendar's representation of time.
time_to_day_fraction(hour, minute, second, arg): Returns the normalized day fraction of the specified time.
time_to_string(hour, minute, second, microsecond, format \\ :extended): Converts the given time into a string.
valid_date?(year, month, day): Determines if the date given is valid according to the proleptic Gregorian calendar.
valid_time?(hour, minute, second, microsecond): Determines if the date given is valid according to the proleptic Gregorian calendar.
year_of_era(year): Calculates the year and era from the given year.

Types

bce()Source

Specs

bce() :: 0

"Before the Current Era" or "Before the Common Era" (BCE), for those years less than 1.

ce()Source

Specs

ce() :: 1

The "Current Era" or the "Common Era" (CE) which starts in year 1.

day()Source

Specs

day() :: 1..31

day_of_week()Source

Specs

day_of_week() :: 1..7

Integer that represents the day of the week, where 1 is Monday and 7 is Sunday.

day_of_year()Source

Specs

day_of_year() :: 1..366

era()Source

Specs

era() :: bce() | ce()

The calendar era.

The ISO calendar has two eras:

CE - which starts in year 1 and is defined as era 1.
BCE - for those years less than 1 and is defined as era 0.

hour()Source

Specs

hour() :: 0..23

microsecond()Source

Specs

microsecond() :: {0..999_999, 0..6}

Microseconds with stored precision.

The precision represents the number of digits that must be used when representing the microseconds to external format. If the precision is 0, it means microseconds must be skipped.

minute()Source

Specs

minute() :: 0..59

month()Source

Specs

month() :: 1..12

quarter_of_year()Source

Specs

quarter_of_year() :: 1..4

second()Source

Specs

second() :: 0..59

weekday()Source

Specs

weekday() ::
  :monday | :tuesday | :wednesday | :thursday | :friday | :saturday | :sunday

year()Source

Specs

year() :: -9999..9999

year_of_era()Source

Specs

year_of_era() :: {1..10000, era()}

Functions

date_to_string(year, month, day, format \\ :extended)Source

Specs

date_to_string(year(), month(), day(), :basic | :extended) :: String.t()

Converts the given date into a string.

By default, returns dates formatted in the "extended" format, for human readability. It also supports the "basic" format by passing the :basic option.

Examples

iex> Calendar.ISO.date_to_string(2015, 2, 28)
"2015-02-28"
iex> Calendar.ISO.date_to_string(2017, 8, 1)
"2017-08-01"
iex> Calendar.ISO.date_to_string(-99, 1, 31)
"-0099-01-31"

iex> Calendar.ISO.date_to_string(2015, 2, 28, :basic)
"20150228"
iex> Calendar.ISO.date_to_string(-99, 1, 31, :basic)
"-00990131"

datetime_to_string(year, month, day, hour, minute, second, microsecond, time_zone, zone_abbr, utc_offset, std_offset, format \\ :extended)Source

Specs

datetime_to_string(
  year(),
  month(),
  day(),
  Calendar.hour(),
  Calendar.minute(),
  Calendar.second(),
  Calendar.microsecond(),
  Calendar.time_zone(),
  Calendar.zone_abbr(),
  Calendar.utc_offset(),
  Calendar.std_offset(),
  :basic | :extended
) :: String.t()

Converts the datetime (with time zone) into a string.

By default, returns datetimes formatted in the "extended" format, for human readability. It also supports the "basic" format by passing the :basic option.

Examples

iex> time_zone = "Etc/UTC"
iex> Calendar.ISO.datetime_to_string(2017, 8, 1, 1, 2, 3, {4, 5}, time_zone, "UTC", 0, 0)
"2017-08-01 01:02:03.00000Z"
iex> Calendar.ISO.datetime_to_string(2017, 8, 1, 1, 2, 3, {4, 5}, time_zone, "UTC", 3600, 0)
"2017-08-01 01:02:03.00000+01:00"
iex> Calendar.ISO.datetime_to_string(2017, 8, 1, 1, 2, 3, {4, 5}, time_zone, "UTC", 3600, 3600)
"2017-08-01 01:02:03.00000+02:00"

iex> time_zone = "Europe/Berlin"
iex> Calendar.ISO.datetime_to_string(2017, 8, 1, 1, 2, 3, {4, 5}, time_zone, "CET", 3600, 0)
"2017-08-01 01:02:03.00000+01:00 CET Europe/Berlin"
iex> Calendar.ISO.datetime_to_string(2017, 8, 1, 1, 2, 3, {4, 5}, time_zone, "CDT", 3600, 3600)
"2017-08-01 01:02:03.00000+02:00 CDT Europe/Berlin"

iex> time_zone = "America/Los_Angeles"
iex> Calendar.ISO.datetime_to_string(2015, 2, 28, 1, 2, 3, {4, 5}, time_zone, "PST", -28800, 0)
"2015-02-28 01:02:03.00000-08:00 PST America/Los_Angeles"
iex> Calendar.ISO.datetime_to_string(2015, 2, 28, 1, 2, 3, {4, 5}, time_zone, "PDT", -28800, 3600)
"2015-02-28 01:02:03.00000-07:00 PDT America/Los_Angeles"

iex> time_zone = "Europe/Berlin"
iex> Calendar.ISO.datetime_to_string(2017, 8, 1, 1, 2, 3, {4, 5}, time_zone, "CET", 3600, 0, :basic)
"20170801 010203.00000+0100 CET Europe/Berlin"

day_of_era(year, month, day)Source

Specs

day_of_era(year(), month(), day()) :: Calendar.day_of_era()

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

Examples

iex> Calendar.ISO.day_of_era(0, 1, 1)
{366, 0}
iex> Calendar.ISO.day_of_era(1, 1, 1)
{1, 1}
iex> Calendar.ISO.day_of_era(0, 12, 31)
{1, 0}
iex> Calendar.ISO.day_of_era(0, 12, 30)
{2, 0}
iex> Calendar.ISO.day_of_era(-1, 12, 31)
{367, 0}

day_of_week(year, month, day, starting_on)Source

Specs

day_of_week(year(), month(), day(), :default | weekday()) ::
  {day_of_week(), 1, 7}

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

It is an integer from 1 to 7, where 1 is the given starting_on weekday. For example, if starting_on is set to :monday, then 1 is Monday and 7 is Sunday.

starting_on can also be :default, which is equivalent to :monday.

Examples

iex> Calendar.ISO.day_of_week(2016, 10, 31, :monday)
{1, 1, 7}
iex> Calendar.ISO.day_of_week(2016, 11, 1, :monday)
{2, 1, 7}
iex> Calendar.ISO.day_of_week(2016, 11, 2, :monday)
{3, 1, 7}
iex> Calendar.ISO.day_of_week(2016, 11, 3, :monday)
{4, 1, 7}
iex> Calendar.ISO.day_of_week(2016, 11, 4, :monday)
{5, 1, 7}
iex> Calendar.ISO.day_of_week(2016, 11, 5, :monday)
{6, 1, 7}
iex> Calendar.ISO.day_of_week(2016, 11, 6, :monday)
{7, 1, 7}
iex> Calendar.ISO.day_of_week(-99, 1, 31, :monday)
{4, 1, 7}

iex> Calendar.ISO.day_of_week(2016, 10, 31, :sunday)
{2, 1, 7}
iex> Calendar.ISO.day_of_week(2016, 11, 1, :sunday)
{3, 1, 7}
iex> Calendar.ISO.day_of_week(2016, 11, 2, :sunday)
{4, 1, 7}
iex> Calendar.ISO.day_of_week(2016, 11, 3, :sunday)
{5, 1, 7}
iex> Calendar.ISO.day_of_week(2016, 11, 4, :sunday)
{6, 1, 7}
iex> Calendar.ISO.day_of_week(2016, 11, 5, :sunday)
{7, 1, 7}
iex> Calendar.ISO.day_of_week(2016, 11, 6, :sunday)
{1, 1, 7}
iex> Calendar.ISO.day_of_week(-99, 1, 31, :sunday)
{5, 1, 7}

iex> Calendar.ISO.day_of_week(2016, 10, 31, :saturday)
{3, 1, 7}

day_of_year(year, month, day)Source

Specs

day_of_year(year(), month(), day()) :: day_of_year()

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

It is an integer from 1 to 366.

Examples

iex> Calendar.ISO.day_of_year(2016, 1, 31)
31
iex> Calendar.ISO.day_of_year(-99, 2, 1)
32
iex> Calendar.ISO.day_of_year(2018, 2, 28)
59

day_rollover_relative_to_midnight_utc()Source

Specs

day_rollover_relative_to_midnight_utc() :: {0, 1}

See Calendar.day_rollover_relative_to_midnight_utc/0 for documentation.

days_in_month(year, month)Source

Specs

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

Returns how many days there are in the given year-month.

Examples

iex> Calendar.ISO.days_in_month(1900, 1)
31
iex> Calendar.ISO.days_in_month(1900, 2)
28
iex> Calendar.ISO.days_in_month(2000, 2)
29
iex> Calendar.ISO.days_in_month(2001, 2)
28
iex> Calendar.ISO.days_in_month(2004, 2)
29
iex> Calendar.ISO.days_in_month(2004, 4)
30
iex> Calendar.ISO.days_in_month(-1, 5)
31

leap_year?(year)Source

Specs

leap_year?(year()) :: boolean()

Returns if the given year is a leap year.

Examples

iex> Calendar.ISO.leap_year?(2000)
true
iex> Calendar.ISO.leap_year?(2001)
false
iex> Calendar.ISO.leap_year?(2004)
true
iex> Calendar.ISO.leap_year?(1900)
false
iex> Calendar.ISO.leap_year?(-4)
true

months_in_year(year)Source

Specs

months_in_year(year()) :: 12

Returns how many months there are in the given year.

Example

iex> Calendar.ISO.months_in_year(2004)
12

naive_datetime_from_iso_days(arg)Source

Specs

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

Converts the Calendar.iso_days/0 format to the datetime format specified by this calendar.

Examples

iex> Calendar.ISO.naive_datetime_from_iso_days({0, {0, 86400}})
{0, 1, 1, 0, 0, 0, {0, 6}}
iex> Calendar.ISO.naive_datetime_from_iso_days({730_485, {0, 86400}})
{2000, 1, 1, 0, 0, 0, {0, 6}}
iex> Calendar.ISO.naive_datetime_from_iso_days({730_485, {43200, 86400}})
{2000, 1, 1, 12, 0, 0, {0, 6}}
iex> Calendar.ISO.naive_datetime_from_iso_days({-365, {0, 86400000000}})
{-1, 1, 1, 0, 0, 0, {0, 6}}

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

Specs

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

Returns the Calendar.iso_days/0 format of the specified date.

Examples

iex> Calendar.ISO.naive_datetime_to_iso_days(0, 1, 1, 0, 0, 0, {0, 6})
{0, {0, 86400000000}}
iex> Calendar.ISO.naive_datetime_to_iso_days(2000, 1, 1, 12, 0, 0, {0, 6})
{730485, {43200000000, 86400000000}}
iex> Calendar.ISO.naive_datetime_to_iso_days(2000, 1, 1, 13, 0, 0, {0, 6})
{730485, {46800000000, 86400000000}}
iex> Calendar.ISO.naive_datetime_to_iso_days(-1, 1, 1, 0, 0, 0, {0, 6})
{-365, {0, 86400000000}}

naive_datetime_to_string(year, month, day, hour, minute, second, microsecond, format \\ :extended)Source

Specs

naive_datetime_to_string(
  year(),
  month(),
  day(),
  Calendar.hour(),
  Calendar.minute(),
  Calendar.second(),
  Calendar.microsecond(),
  :basic | :extended
) :: String.t()

Converts the datetime (without time zone) into a string.

By default, returns datetimes formatted in the "extended" format, for human readability. It also supports the "basic" format by passing the :basic option.