View Source Calendar.ISO (Elixir v1.12.0-rc.1)
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}Link to this section Summary
Types
"Before the Current Era" or "Before the Common Era" (BCE), for those years less than 1.
The "Current Era" or the "Common Era" (CE) which starts in year 1.
Integer that represents the day of the week, where 1 is Monday and 7 is Sunday.
The calendar era.
Microseconds with stored precision.
Functions
Converts the given date into a string.
Converts the datetime (with time zone) into a string.
Calculates the day and era from the given year, month, and day.
Calculates the day of the week from the given year, month, and day.
Calculates the day of the year from the given year, month, and day.
See Calendar.day_rollover_relative_to_midnight_utc/0 for documentation.
Returns how many days there are in the given year-month.
Returns if the given year is a leap year.
Returns how many months there are in the given year.
Converts the Calendar.iso_days/0 format to the datetime format specified by this calendar.
Returns the Calendar.iso_days/0 format of the specified date.
Converts the datetime (without time zone) into a string.
Parses a date string in the :extended format.
Parses a date string according to a given format.
Parses a naive datetime string in the :extended format.
Parses a naive datetime string according to a given format.
Parses a time string in the :extended format.
Parses a time string according to a given format.
Parses a UTC datetime string in the :extended format.
Parses a UTC datetime string according to a given format.
Calculates the quarter of the year from the given year, month, and day.
Converts a day fraction to this Calendar's representation of time.
Returns the normalized day fraction of the specified time.
Converts the given time into a string.
Determines if the date given is valid according to the proleptic Gregorian calendar.
Determines if the date given is valid according to the proleptic Gregorian calendar.
Calculates the year and era from the given year.
Link to this section Types
@type bce() :: 0
"Before the Current Era" or "Before the Common Era" (BCE), for those years less than 1.
@type ce() :: 1
The "Current Era" or the "Common Era" (CE) which starts in year 1.
@type day() :: 1..31
@type day_of_week() :: 1..7
Integer that represents the day of the week, where 1 is Monday and 7 is Sunday.
@type day_of_year() :: 1..366
The calendar era.
The ISO calendar has two eras:
@type hour() :: 0..23
@type 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.
@type minute() :: 0..59
@type month() :: 1..12
@type quarter_of_year() :: 1..4
@type second() :: 0..59
@type weekday() ::
:monday | :tuesday | :wednesday | :thursday | :friday | :saturday | :sunday
@type year() :: -9999..9999
@type year_of_era() :: {1..10000, era()}
Link to this section Functions
date_to_string(year, month, day, format \\ :extended)
View Source (since 1.4.0)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)
View Source (since 1.4.0)@spec 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"@spec 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}@spec 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}@spec 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@spec day_rollover_relative_to_midnight_utc() :: {0, 1}
See Calendar.day_rollover_relative_to_midnight_utc/0 for documentation.
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)
31Returns 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@spec months_in_year(year()) :: 12
Returns how many months there are in the given year.
Example
iex> Calendar.ISO.months_in_year(2004)
12@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 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)
View Source (since 1.5.0)@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 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)
View Source (since 1.4.0)@spec 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.
Examples
iex> Calendar.ISO.naive_datetime_to_string(2015, 2, 28, 1, 2, 3, {4, 6})
"2015-02-28 01:02:03.000004"
iex> Calendar.ISO.naive_datetime_to_string(2017, 8, 1, 1, 2, 3, {4, 5})
"2017-08-01 01:02:03.00000"
iex> Calendar.ISO.naive_datetime_to_string(2015, 2, 28, 1, 2, 3, {4, 6}, :basic)
"20150228 010203.000004"Parses a date string in the :extended format.
For more information on supported strings, see how this module implements ISO 8601.
Examples
iex> Calendar.ISO.parse_date("2015-01-23")
{:ok, {2015, 1, 23}}
iex> Calendar.ISO.parse_date("2015:01:23")
{:error, :invalid_format}
iex> Calendar.ISO.parse_date("2015-01-32")
{:error, :invalid_date}Parses a date string according to a given format.
The format can either be :basic or :extended.
For more information on supported strings, see how this module implements ISO 8601.
Examples
iex> Calendar.ISO.parse_date("20150123", :basic)
{:ok, {2015, 1, 23}}
iex> Calendar.ISO.parse_date("20150123", :extended)
{:error, :invalid_format}Parses a naive datetime string in the :extended format.
For more information on supported strings, see how this module implements ISO 8601.
Examples
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 23:50:07Z")
{:ok, {2015, 1, 23, 23, 50, 7, {0, 0}}}
iex> Calendar.ISO.parse_naive_datetime("2015-01-23 23:50:07-02:30")
{:ok, {2015, 1, 23, 23, 50, 7, {0, 0}}}
iex> Calendar.ISO.parse_naive_datetime("2015-01-23 23:50:07.0")
{:ok, {2015, 1, 23, 23, 50, 7, {0, 1}}}
iex> Calendar.ISO.parse_naive_datetime("2015-01-23 23:50:07,0123456")
{:ok, {2015, 1, 23, 23, 50, 7, {12345, 6}}}Parses a naive datetime string according to a given format.
The format can either be :basic or :extended.
For more information on supported strings, see how this module implements ISO 8601.
Examples
iex> Calendar.ISO.parse_naive_datetime("20150123 235007", :basic)
{:ok, {2015, 1, 23, 23, 50, 7, {0, 0}}}
iex> Calendar.ISO.parse_naive_datetime("20150123 235007", :extended)
{:error, :invalid_format}Parses a time string in the :extended format.
For more information on supported strings, see how this module implements ISO 8601.
Examples
iex> Calendar.ISO.parse_time("23:50:07")
{:ok, {23, 50, 7, {0, 0}}}
iex> Calendar.ISO.parse_time("23:50:07Z")
{:ok, {23, 50, 7, {0, 0}}}
iex> Calendar.ISO.parse_time("T23:50:07Z")
{:ok, {23, 50, 7, {0, 0}}}Parses a time string according to a given format.
The format can either be :basic or :extended.
For more information on supported strings, see how this module implements ISO 8601.
Examples
iex> Calendar.ISO.parse_time("235007", :basic)
{:ok, {23, 50, 7, {0, 0}}}
iex> Calendar.ISO.parse_time("235007", :extended)
{:error, :invalid_format}Parses a UTC datetime string in the :extended format.
For more information on supported strings, see how this module implements ISO 8601.
Examples
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 23:50:07+02:30")
{:ok, {2015, 1, 23, 21, 20, 7, {0, 0}}, 9000}
iex> Calendar.ISO.parse_utc_datetime("2015-01-23 23:50:07")
{:error, :missing_offset}Parses a UTC datetime string according to a given format.
The format can either be :basic or :extended.
For more information on supported strings, see how this module implements ISO 8601.
Examples
iex> Calendar.ISO.parse_utc_datetime("20150123 235007Z", :basic)
{:ok, {2015, 1, 23, 23, 50, 7, {0, 0}}, 0}
iex> Calendar.ISO.parse_utc_datetime("20150123 235007Z", :extended)
{:error, :invalid_format}@spec quarter_of_year(year(), month(), day()) :: quarter_of_year()
Calculates the quarter of the year from the given year, month, and day.
It is an integer from 1 to 4.
Examples
iex> Calendar.ISO.quarter_of_year(2016, 1, 31)
1
iex> Calendar.ISO.quarter_of_year(2016, 4, 3)
2
iex> Calendar.ISO.quarter_of_year(-99, 9, 31)
3
iex> Calendar.ISO.quarter_of_year(2018, 12, 28)
4@spec time_from_day_fraction(Calendar.day_fraction()) :: {hour(), minute(), second(), microsecond()}
Converts a day fraction to this Calendar's representation of time.
Examples
iex> Calendar.ISO.time_from_day_fraction({1, 2})
{12, 0, 0, {0, 6}}
iex> Calendar.ISO.time_from_day_fraction({13, 24})
{13, 0, 0, {0, 6}}@spec time_to_day_fraction( Calendar.hour(), Calendar.minute(), Calendar.second(), Calendar.microsecond() ) :: Calendar.day_fraction()
Returns the normalized day fraction of the specified time.
Examples
iex> Calendar.ISO.time_to_day_fraction(0, 0, 0, {0, 6})
{0, 86400000000}
iex> Calendar.ISO.time_to_day_fraction(12, 34, 56, {123, 6})
{45296000123, 86400000000}time_to_string(hour, minute, second, microsecond, format \\ :extended)
View Source (since 1.5.0)@spec time_to_string( Calendar.hour(), Calendar.minute(), Calendar.second(), Calendar.microsecond(), :basic | :extended ) :: String.t()
Converts the given time into a string.
By default, returns times formatted in the "extended" format,
for human readability. It also supports the "basic" format
by passing the :basic option.
Examples
iex> Calendar.ISO.time_to_string(2, 2, 2, {2, 6})
"02:02:02.000002"
iex> Calendar.ISO.time_to_string(2, 2, 2, {2, 2})
"02:02:02.00"
iex> Calendar.ISO.time_to_string(2, 2, 2, {2, 0})
"02:02:02"
iex> Calendar.ISO.time_to_string(2, 2, 2, {2, 6}, :basic)
"020202.000002"
iex> Calendar.ISO.time_to_string(2, 2, 2, {2, 6}, :extended)
"02:02:02.000002"Determines if the date given is valid according to the proleptic Gregorian calendar.
Examples
iex> Calendar.ISO.valid_date?(2015, 2, 28)
true
iex> Calendar.ISO.valid_date?(2015, 2, 30)
false
iex> Calendar.ISO.valid_date?(-1, 12, 31)
true
iex> Calendar.ISO.valid_date?(-1, 12, 32)
false@spec valid_time?( Calendar.hour(), Calendar.minute(), Calendar.second(), Calendar.microsecond() ) :: boolean()
Determines if the date given is valid according to the proleptic Gregorian calendar.
Leap seconds are not supported by the built-in Calendar.ISO.
Examples
iex> Calendar.ISO.valid_time?(10, 50, 25, {3006, 6})
true
iex> Calendar.ISO.valid_time?(23, 59, 60, {0, 0})
false
iex> Calendar.ISO.valid_time?(24, 0, 0, {0, 0})
falseCalculates the year and era from the given year.
The ISO calendar has two eras: the "current era" (CE) which
starts in year 1 and is defined as era 1. And "before the current
era" (BCE) for those years less than 1, defined as era 0.
Examples
iex> Calendar.ISO.year_of_era(1)
{1, 1}
iex> Calendar.ISO.year_of_era(2018)
{2018, 1}
iex> Calendar.ISO.year_of_era(0)
{1, 0}
iex> Calendar.ISO.year_of_era(-1)
{2, 0}