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srfi-19

Time Data Types and Procedures

srfi-19
Documentation
Usage
SRFI 29 bundles
Examples
Notes
Bugs and Limitations
Requirements
Author
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Documentation

This is a Chicken port of SRFI-19. This document only describes the extensions. For the SRFI-19 API see SRFI-19.

Core Procedures

The core procedures are those pertaining to time, date, and timezone:

(import srfi-19-core)

Or separately:

(import srfi-19-time)

(import srfi-19-date)

(import srfi-19-timezone)

(import srfi-19-support)

SRFI-19 Document Changes

The nanosecond time object element is an integer between 0 and 999,999,999 inclusive. (The SRFI-19 document mis-states the value.)

A tz-offset value follows ISO 8601; positive for east of UTC, and negative for west. This is the opposite of the POSIX TZ environment variable.

Where the SRFI-19 document states a tz-offset argument a timezone-components object is also legal; see Timezone

The string->date procedure allows the template-name argument to be optional. When missing the locale's date-time-format string is used. The supplied locale bundle's strings are invertible.

make-date

[procedure] (make-date NANOSECOND SECOND MINUTE HOUR DAY MONTH YEAR [ZONE-OFFSET [TZ-NAME [DST-FLAG]]])

Same as SRFI-19 except for the optional parameters and allowing a timezone-components object for the ZONE-OFFSET.

The ZONE-OFFSET is an integer or timezone-components. Default is the (timezone-locale-offset), the current locale timezone offset.

The TZ-NAME is a string or #f, and is the timezone name. Default is #f.

The DST-FLAG is a boolean, and indicates whether Day Saving TIme (or Summer Time) is active. Default is #f.

When the ZONE-OFFSET is a timezone-components object the TZ-NAME and DST-FLAG are pulled from the timezone-components, unless explicitly supplied.

read-leap-second-table

[procedure] (read-leap-second-table FILENAME)

Sets the leap second table from the specified FILENAME.

The file format is the same as the "tai-utc.dat" file in the distribution. Provided by the U.S. Naval Observatory.

leap-year?

[procedure] (leap-year? DATE)

Does the specified DATE fall on a leap year?

The DATE may be a numeric year or a date object.

SRFI-18 Time

Note that the SRFI-18 identifiers time?, current-time, seconds->time, time->seconds, milliseconds->time, and time->milliseconds are in conflict with those of SRFI-19.

time->srfi-18-time

[procedure] (time->srfi-18-time TIME)

Converts a SRFI-19 time object to a SRFI-18 time object. The conversion is really only meaningful for time-duration, but any time-type is accepted.

srfi-18-time->time

[procedure] (srfi-18-time->time TIME)

Converts a SRFI-18 time object into a SRFI-19 time-duration object.

Time Conversion

time-hash

[procedure] (time-hash TIME #!optional bnd rnd)

Hash TIME.

time-copy

[procedure] (time-copy TIME)

Returns an exact copy of the specified TIME object.

seconds->time

[procedure] (seconds->time SECONDS [TIME-TYPE time-duration])

Converts a SECONDS value, may be fractional, into a TIME-TYPE time object.

seconds->date

[procedure] (seconds->date SECONDS [TIMEZONE-INFO #t])

Converts a SECONDS value, which may be fractional, into a date object. The TIMEZONE-INFO is #t for the local timezone, #f for the utc timezone, or a timezone-components object.

SECONDS is relative to 00:00:00 January 1, 1970 UTC.

time->nanoseconds

[procedure] (time->nanoseconds TIME)

Returns the TIME object value as a nanoseconds value.

nanoseconds->time

[procedure] (nanoseconds->time NANOSECONDS [TIME-TYPE time-duration])

Returns the NANOSECONDS value as a time TIME-TYPE object.

nanoseconds->seconds

[procedure] (nanoseconds->seconds NANOSECONDS)

Returns the NANOSECONDS value as a seconds value.

time->milliseconds

[procedure] (time->milliseconds TIME)

Returns the TIME object value as a milliseconds value.

milliseconds->time

[procedure] (milliseconds->time MILLISECONDS [TIME-TYPE time-duration])

Returns the MILLISECONDS value as a time TIME-TYPE object.

milliseconds->seconds

[procedure] (milliseconds->seconds MILLISECONDS)

Returns the MILLISECONDS value as a seconds value.

time->date

[procedure] (time->date TIME)

Returns the TIME object value as a date. A shorthand for the (time-*->date...) procedures.

time->julian-day

[procedure] (time->julian-day TIME)

Returns the julian day for the TIME object.

time->modified-julian-day

[procedure] (time->modified-julian-day TIME)

Returns the modified julian day for the TIME object.

thread-time

[procedure] (monotonic-time)
[procedure] (utc-time)
[procedure] (tai-time)
[procedure] (gc-time)
[procedure] (process-time)
[procedure] (thread-time)

Return current time for the named time type.

From Chibi (srfi 19) (https://github.com/OpinionatedGeek/SRFI19):

Time Arithmetic

make-duration

[procedure] (make-duration [#:days 0] [#:hours 0] [#:minutes 0] [#:seconds 0] [#:milliseconds 0] [#:microseconds 0] [#:nanoseconds 0])

Returns a time-object of clock-type time-duration where the seconds and nanoseconds values are calculated by summing the keyword arguments.

one-nanosecond-duration

[procedure] (one-nanosecond-duration)

zero-time

[procedure] (zero-time [TIME-TYPE time-duration])

TIME-FINE-GRAIN

Most minimum positive amount of time, as a duration.

divide-duration

[procedure] (divide-duration DURATION REAL)

Returns a duration, from DURATION, divided by REAL, without remainder.

divide-duration!

[procedure] (divide-duration! DURATION REAL)

Returns DURATION, divided by REAL, without remainder.

multiply-duration

[procedure] (multiply-duration DURATION REAL)

Returns a duration, from DURATION, multiplied by REAL, truncated.

multiply-duration!

[procedure] (multiply-duration! DURATION REAL)

Returns DURATION, multiplied by REAL, truncated.

time-negative?

[procedure] (time-negative? TIME)

Is TIME negative?

A time object will never have a negative nanoseconds value.

time-positve?

[procedure] (time-positve? TIME)

Is TIME positive?

time-zero?

[procedure] (time-zero? TIME)

Is TIME zero?

time-abs

[procedure] (time-abs TIME)

Returns the absolute time value, from TIME.

time-abs!

[procedure] (time-abs! TIME)

Returns the absolute TIME value.

time-negate

[procedure] (time-negate TIME)

Returns the sign inverted time value, from TIME.

time-negate!

[procedure] (time-negate! TIME)

Returns the TIME sign inverted value.

Time Comparison

time-compare

[procedure] (time-compare TIME1 TIME2)

Returns -1, 0, or 1.

time-max

[procedure] (time-max TIME1 [TIME2...])

Returns the maximum time object from TIME1 TIME2....

time-min

[procedure] (time-min TIME1 [TIME2...])

Returns the minimum time object from TIME1 TIME2....

Dates

default-date-clock-type

[parameter] (default-date-clock-type [CLOCK-TYPE time-utc]) -> symbol

Sets or gets the clock-type used by default for conversion of a date to a time.

date-copy

[procedure] (date-copy DATE)

Returns an exact copy of the specified DATE object.

date->seconds

[procedure] (date->seconds DATE [CLOCK-TYPE (default-date-clock-type)])

Returns the specified DATE as as a seconds value, based on the CLOCK-TYPE.

The seconds value is relative to the TAI-EPOCH - 1 January 1970 CE at 00:00:00 UTC.

date->time

[procedure] (date->time DATE [CLOCK-TYPE (default-date-clock-type)])

Returns the specified DATE as a time-object of type CLOCK-TYPE.

date-zone-name

[procedure] (date-zone-name DATE)
[procedure] (date-zone-name DATE)

Returns the timezone abbreviation of the specified DATE object. The result is either a string or #f.

date-dst?

[procedure] (date-dst? DATE)

Returns the daylight saving time flag of the specified DATE object.

Only valid for "current" dates. Historical dates will not have a correct setting. Future dates cannot have a correct setting.

Date Arithmetic

date-difference

[procedure] (date-difference DATE1 DATE2 [CLOCK-TYPE])

Returns the time-duration between DATE1 and DATE2.

date-add-duration

[procedure] (date-add-duration DATE DURATION [CLOCK-TYPE])

Returns a new date, the DATE plus the DURATION.

date-subtract-duration

[procedure] (date-subtract-duration DATE DURATION [CLOCK-TYPE])

Returns a new date, the DATE minus the DURATION.

date-adjust

[procedure] (date-adjust DATE AMOUNT KEY [CLOCK-TYPE])

Returns a new date, the DATE adjusted by the AMOUNT of KEY.

AMOUNT: integer ;
KEY: symbol ; '(years quarters months weeks days hours minutes seconds milliseconds microseconds nanoseconds).

If the day of the month of DATE is greater than the number of days in the final month, the day of the month will change to the last day in the final month.

Adjusting a time KEY (ex: 'hours) follows the semantics of date-add-duration.

date-adjust*

[procedure] (date-adjust* DATE KEY AMOUNT ... [CLOCK-TYPE])

Returns a new date, the DATE adjusted by each of the KEY AMOUNT pairs, in-order.

AMOUNT: integer ;
KEY: keyword ; '(#:years #:quarters #:months #:weeks #:days #:hours #:minutes #:seconds #:milliseconds #:microseconds #:nanoseconds).

A convince wrapper of date-adjust.

Date Comparison

date-compare

[procedure] (date-compare DATE1 DATE2)

Returns -1, 0, or 1.

date-hash

[procedure] (date-hash DATE #!optional bnd rnd)

Hash DATE.

date=?

[procedure] (date=? DATE1 DATE2)

Is DATE1 on DATE2?

date>?

[procedure] (date>? DATE1 DATE2)

Is DATE1 after DATE2?

date<?

[procedure] (date<? DATE1 DATE2)

Is DATE1 before DATE2?

date>=?

[procedure] (date>=? DATE1 DATE2)

Is DATE1 after or on DATE2?

date<=?

[procedure] (date<=? DATE1 DATE2)

Is DATE1 before or on DATE2?

Timezone

The daylight saving time (summer time) flag is always taken from the system, unless supplied. Any summer time rule component of a timezone-components object is not processed.

TZ-COMPONENTS: timezone-components ;a timezone object

SRFI-19 timezone offset follows ISO 8601; positive for east of UTC, and negative for west. This is the opposite of the POSIX TZ environment variable.

local-timezone-locale

[parameter] (local-timezone-locale [TZ-COMPONENTS])

Gets or sets the local timezone-locale object.

utc-timezone-locale

[parameter] (utc-timezone-locale [TZ-COMPONENTS])

Gets or sets the utc timezone-locale object.

Not a good idea to change the value.

timezone-locale-name

[procedure] (timezone-locale-name [TZ-COMPONENTS])

Returns the timezone-locale name of the supplied TZ-COMPONENTS, or the (local-timezone-locale) if missing.

timezone-locale-offset

[procedure] (timezone-locale-offset [TZ-COMPONENTS])

Returns the timezone-locale offset of the supplied TZ-COMPONENTS, or the (local-timezone-locale) if missing.

timezone-locale-dst?

[procedure] (timezone-locale-dst? [TZ-COMPONENTS])

Returns the timezone-locale daylight saving time flag of the supplied TZ-COMPONENTS, or the (local-timezone-locale) if missing.

Input/Output Procedures

(import srfi-19-io)

DATE->STRING conversion specifiers

The SRFI-19 document does not mention the padding character override feature for the normally zero-padded conversions f, H, I, j, m, M, N, S, y. If the tilde is followed by a - then padding is suppressed. If followed by a _ the space character is used for padding. Otherwise zero-padding is perfomed, the default.

~[-_][fHIjmMNSy]

From Chibi (srfi 19) (https://github.com/OpinionatedGeek/SRFI19):

g - day of month. It just outputs the day of the month (1...31). The other two standard directives both specify either blank padding or zero padding but there's no option for no padding.
u - day ordinal suffix. Outputs the locale-specific suffix for the day of the month. For example "rd" for 3, "th" for 6, or "st" for 21. This allows you to format dates as "Sunday, 1st of January 2017". It's possible to insert the "st" in such a format string manually but it doesn't seem a clean approach.

format-date

[procedure] (format-date DESTINATION DATE-FORMAT DATE)
[procedure] (format-date DATE-FORMAT DATE)

Displays a text form of the DATE on the DESTINATION using the DATE-FORMAT.

DESTINATION: ; the result is returned as a string.
DESTINATION: #f ; the result is returned as a string.
DESTINATION: #t ; the (current-output-port) is used.
DESTINATION: output-port ; text output port.
DESTINATION: number ; the (current-error-port) is the DESTINATION.

scan-date

[procedure] (scan-date SOURCE TEMPLATE)

Reads a text form of a date from the SOURCE, following the TEMPLATE, and returns a date object.

SOURCE: #t ; (current-input-port).
SOURCE: input-port ; text input port.
SOURCE: string ; a date text form.

A partial date resulting from a time-only format, missing the d-m-y, is completed with from the (current-date), as is any timezone information, and missing h:m:s:ns are 0.

string->date

[procedure] (string->date SOURCE [TEMPLATE])

SOURCE: see scan-date.
TEMPLATE: string ; default (localized-template/default 'srfi-19 'date-time).

date->string

[procedure] (date->string DATE [DATE-FORMAT])

DATE: date
DATE-FORMAT: string ; default "~c".

Date/Time Literals

Literal Date/Time forms.

Usage

(import srfi-19-literals)

date-literal-form

[parameter] (date-literal-form [FORM]) -> boolean
[parameter] (date-literal-form [FORM]) -> symbol

The date literal format.

#f: #<srfi-19#date ...>
SRFI-10: #,(srfi-19-date ...)
#t: #@... ; the default
|#@|: #@...

time-literal-form

[parameter] (time-literal-form [FORM])-> boolean
[parameter] (time-literal-form [FORM])-> symbol

The time literal format.

#f: #<srfi-19#time ...>
SRFI-10: #,(srfi-19-time ...) ; the default
#t ##...
|##|: ##...

Use the ## form at your peril.

read-date-literal

[procedure] (read-date-literal [PORT])

Read a date-literal from the PORT, in one of the supported forms, and return the object creation source form; '(make-date ....).

PORT: input-port ; default (current-input-port)

Supported forms:

"~Y-~m-~dT~H:~M:~S~z": date time timezone
"~Y-~m-~dT~H:~M:~S": date time
"~Y-~m-~d": date
"~H:~M:~S~z": time timezone; date components from (current-date)
"~H:~M:~S": time; date components from (current-date)

write-date-literal

[procedure] (write-date-literal DATE [PORT])

Write the DATE to the PORT using a string ISO form; "~Y-~m-~dT~H:~M:~S~z".

PORT: output-port ; default (current-output-port)

Time Period

Usage

(import srfi-19-period)

A time-period is an interval, [begin end), where begin and end are time objects of the same clock type.

make-time-period

[procedure] (make-time-period BEGIN END [CLOCK-TYPE (default-date-clock-type)])

Returns a new time-period object. The clock types must be compatible.

BEGIN maybe a seconds value, a date, or a time (except time-duration). A seconds value or date are converted to CLOCK-TYPE.

END maybe a seconds value, a date, or a time. A seconds value or date are converted to the same clock type as BEGIN. A time-duration is treated as an offset from BEGIN.

time-period-copy

[procedure] (time-period-copy TIME-PERIOD)

Returns a copy of TIME-PERIOD.

time-period-begin

[procedure] (time-period-begin TIME-PERIOD)

Returns the start time for the TIME-PERIOD.

time-period-end

[procedure] (time-period-end TIME-PERIOD)

Returns the end time for the TIME-PERIOD.

time-period-last

[procedure] (time-period-last TIME-PERIOD)

Returns the last time for the TIME-PERIOD; (time-period-end - TIME-FINE-GRAIN).

time-period-type

[procedure] (time-period-type TIME-PERIOD)

Returns the clock-type of the TIME-PERIOD.

time-period?

[procedure] (time-period? OBJECT)

Is OBJECT a time-period?

time-period-length

[procedure] (time-period-length TIME-PERIOD)

Returns the time-duration of the TIME-PERIOD.

time-period-hash

[procedure] (time-period-hash TIME-PERIOD #!optional bnd rnd)

Hash TIME-PERIOD.

time-period-compare

[procedure] (time-period-compare TIME-PERIOD-1 TIME-PERIOD-2)

Returns -1 when TIME-PERIOD-1 < TIME-PERIOD-2, 0 when TIME-PERIOD-1 = TIME-PERIOD-2 and 1 TIME-PERIOD-1 > TIME-PERIOD-2.

time-period=?

[procedure] (time-period=? TIME-PERIOD-1 TIME-PERIOD-2)

Does TIME-PERIOD-1 begin & end with TIME-PERIOD-2?

time-period<?

[procedure] (time-period<? TIME-PERIOD-1 TIME-PERIOD-2)

Does TIME-PERIOD-1 end before TIME-PERIOD-2 begins?

time-period>?

[procedure] (time-period>? TIME-PERIOD-1 TIME-PERIOD-2)

Does TIME-PERIOD-1 begin after TIME-PERIOD-2 ends?

time-period<=?

[procedure] (time-period<=? TIME-PERIOD-1 TIME-PERIOD-2)

Does TIME-PERIOD-1 end on or before TIME-PERIOD-2 begins?

time-period>=?

[procedure] (time-period>=? TIME-PERIOD-1 TIME-PERIOD-2)

Does TIME-PERIOD-1 begin on or after TIME-PERIOD-2 ends?

time-period-preceding

[procedure] (time-period-preceding TIME-PERIOD-1 TIME-PERIOD-2)
[procedure] (time-period-preceding TIME-PERIOD-1 TIME-PERIOD-2)

Return the portion of TIME-PERIOD-1 before TIME-PERIOD-2 or #f when it doesn't precede.

time-period-succeeding

[procedure] (time-period-succeeding TIME-PERIOD-1 TIME-PERIOD-2)
[procedure] (time-period-succeeding TIME-PERIOD-1 TIME-PERIOD-2)

Return the portion of TIME-PERIOD-1 after TIME-PERIOD-2 or #f when it doesn't succeed.

time-period-contains/period?

[procedure] (time-period-contains/period? TIME-PERIOD-1 TIME-PERIOD-2)

Is TIME-PERIOD-2 within TIME-PERIOD-1?

time-period-contains/time?

[procedure] (time-period-contains/time? TIME-PERIOD TIME)

Is TIME within TIME-PERIOD?

TIME is converted to a compatible clock-type if possible.

time-period-contains/date?

[procedure] (time-period-contains/date? TIME-PERIOD DATE)

Is DATE within TIME-PERIOD?

DATE is converted to a compatible time if possible.

time-period-contains?

[procedure] (time-period-contains? TIME-PERIOD OBJECT)

Is OBJECT within TIME-PERIOD?

OBJECT maybe a time, date, or time-period.

time-period-intersects?

[procedure] (time-period-intersects? TIME-PERIOD-1 TIME-PERIOD-2)

Does TIME-PERIOD-2 overlap TIME-PERIOD-1?

time-period-intersection

[procedure] (time-period-intersection TIME-PERIOD-1 TIME-PERIOD-2)
[procedure] (time-period-intersection TIME-PERIOD-1 TIME-PERIOD-2)

The overlapping time-period of TIME-PERIOD-2 and TIME-PERIOD-1, or #f when no overlap.

time-period-union

[procedure] (time-period-union TIME-PERIOD-1 TIME-PERIOD-2)
[procedure] (time-period-union TIME-PERIOD-1 TIME-PERIOD-2)

Returns the time-period spanned by TIME-PERIOD-1 and TIME-PERIOD-2, or #f when they do not intersect.

time-period-span

[procedure] (time-period-span TIME-PERIOD-1 TIME-PERIOD-2)

Returns the time-period spanned by TIME-PERIOD-1 and TIME-PERIOD-2, including any gaps.

time-period-shift

[procedure] (time-period-shift TIME-PERIOD DURATION)

Returns a copy of TIME-PERIOD shifted by DURATION.

time-period-shift!

[procedure] (time-period-shift! TIME-PERIOD DURATION)

Returns TIME-PERIOD shifted by DURATION.

Usage

This module exports the time, date, timezone, literal, and io APIs.

(import srfi-19)

SRFI 29 bundles

Installed w/ the egg are:

c: C - c => en
en: English - only shipping u support at the moment.
de: German
it: Italian
es: Spanish
nl: Dutch
pt_br: Brazilian Portuguese

Examples

Prevent default timezone initialization by explicitly setting the 'timezone.

;must be done before 1st invocation of a srfi-19 export
(import locale)
(set-locale-category! 'timezone
  (posix-timezone-string->timezone-components
    ;some acceptable posix tz form
    "XSX+2:00XDX+1:00:00"
    ;source of tz info
    '("POSIX" "TZ")))

(current-timezone-components)
;=> ((tag . timezone) (name . "XSX+2:00XDX+1:00:00") (source "POSIX" "TZ")
;=> (std-name . "XSX") (std-offset . 7200) (dst-name . "XDX") (dst-offset . 3600)
;=> (dst? . #t))

;now we can use srfi-19 in our runtime tz
(import (chicken format))
(import srfi-19)
(format #t "Present Day: ~A~%Present Time: ~A~%: Hah, hah, hah.~%"
  (current-date) (current-time))

Provide SRFI-128 comparators.

(import (only (srfi 128) make-comparator))

(define (make-date-comparator)
  (import (only srfi-19-date date? date=? date<? date-hash))
  (make-comparator date? date=? date<? date-hash) )

(define (make-time-comparator)
  (import (only srfi-19-time time? time=? time<? time-hash))
  (make-comparator time? time=? time<? time-hash) )

(define (make-time-period-comparator)
  (import (only srfi-19-period time-period? time-period=? time-period<? time-period-hash))
  (only srfi-19-period time-period? time-period=? time-period<? time-period-hash) )

Notes

The string->date and scan-date procedures will not create an incomplete date. At a minimum the input must include day, month and year or hour, minute, second; the time and timezone default to 0 and the locale, respectively.
Year 0 is supported per ISO 8601 & XML Date.
The SRFI-18 current-time and time? bindings conflict with SRFI-19 bindings.
A SRFI-18 time object is not accepted except by the conversion procedures.
The English (en) SRFI 29 bundle is American.

Bugs and Limitations

Local timezone information is not necessarily valid for historic dates and problematic for future dates. Daylight saving time is especially an issue. Conversion of a time or seconds value to a local date will use the current timezone offset value. The current offset will reflect the daylight saving time status. So target dates outside of the DST period will be converted incorrectly!
Will only read years in the range 0..9999 properly. The ISO 8601 year convention for years 1 BCE and before and years 10000 CE and after is not supported.
Cannot swap SRFI 29 bundle. Fixed at load time.
Using date-adjust for the same date-key MomentJS says:

If you are adding hours, minutes, seconds, or milliseconds, the assumption is that you want precision to the hour, and will result in a different hour.

var m = moment(new Date(2011, 2, 12, 5, 0, 0)); // the day before DST in the US
m.hours(); // 5
m.add(24, 'hours').hours(); // 6

but this implementation says 1 day = 24 hours, so same hour.

The omnibus modules, srf-19-core & srf-19, do not have accurate type or lambda-info. Use the component modules.
See SRFI 29 bundles for u conversion support.
SRFI 69 is used to process the CHICKEN hash function optionals.

Requirements

utf8 srfi-1 srfi-18 srfi-29 srfi-69 miscmacros locale record-variants check-errors

Test Only

format

Author

Kon Lovett

Repository

This egg is hosted on the CHICKEN Subversion repository:

https://anonymous@code.call-cc.org/svn/chicken-eggs/release/5/srfi-19

If you want to check out the source code repository of this egg and you are not familiar with Subversion, see this page.

Acknowledgments

Special thanks for the German (de), Italian (it), Spanish (es), Dutch (nl), and Brazilian Portuguese (pt_br) SRFI 29 bundles.
The date-literal is copied from the CHICKEN 4 egg date-literals by Arto Bendiken.

Version history

4.8.1: Better date/time-hash. Fix time-compare negative seconds. nanoseconds->time, milliseconds->time, seconds->time, & date->seconds have optional. time-abs & time-negate affect time-second only.
4.8.0: Add Chibi time routines. Fix seconds->time & time->seconds negative seconds.
4.7.5: Add default locale bundle.
4.7.4: Add C locale bundle.
4.7.3: make-date accepts year 0.
4.7.2: date-adjust* accepts symbols.
4.7.1: Fix date<?/date>? swapped bug; reported on #irc by gahr, Jan 26 '23
4.7.0: Add Chibi ~g & ~u output conversion specifiers.
4.6.0: Add date-adjust*.
4.5.2: Better time-literal-form default.
4.5.1: Fix SRFI-69 compatible time-hash, date-hash, time-period-hash.
4.5.0: Add SRFI-69/128 compatible time-hash, date-hash, time-period-hash.
4.4.10: Indicate pure procedures. Fix time conversion procedure signatures.
4.4.9: Add strong typing.
4.4.8: Fix time-copy, add time-copy/date-copy, deprecate copy-date && copy-time, add time-period interval relations.
4.4.7: .
4.4.6: Fix time-utc->date default TZ.
4.4.0: Add Date/Time source literals via the srfi-19-literals module.
4.3.2: Allow partial (time only) date read.
4.3.1: .
4.3.0: Deprecate 'srfi-10 record print form. Fix record printing.
4.3.0: nanoseconds->seconds, milliseconds->seconds, & date->seconds do not necessarily return an inexact.
4.2.1: .
4.2.0: Fix make-date w/o tz.
4.1.2: .
4.1.1: Fix seconds->date flonum argument handling.
4.1.0: Variants.
4.0.2: Add dependencies.
4.0.1: Add dependencies.
4.0.0: C5 port.

License

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the Software), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

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srfi-19

Documentation

Core Procedures

SRFI-19 Document Changes

make-date

read-leap-second-table

leap-year?

SRFI-18 Time

time->srfi-18-time

srfi-18-time->time

Time Conversion

time-hash

time-copy

seconds->time

seconds->date

time->nanoseconds

nanoseconds->time

nanoseconds->seconds

time->milliseconds

milliseconds->time

milliseconds->seconds

time->date

time->julian-day

time->modified-julian-day

monotonic-time

utc-time

tai-time

gc-time

process-time

thread-time

Time Arithmetic

make-duration

one-second-duration

one-nanosecond-duration

zero-time

TIME-FINE-GRAIN

divide-duration

divide-duration!

multiply-duration

multiply-duration!

time-negative?

time-positve?

time-zero?

time-abs

time-abs!

time-negate

time-negate!

Time Comparison

time-compare

time-max

time-min

Dates

default-date-clock-type

date-copy

date->seconds

date->time

date-zone-name

date-dst?

Date Arithmetic

date-difference

date-add-duration

date-subtract-duration

date-adjust

date-adjust*

Date Comparison

date-compare

date-hash

date=?

date>?

date<?

date>=?

date<=?

Timezone

local-timezone-locale

utc-timezone-locale

timezone-locale-name

timezone-locale-offset

timezone-locale-dst?

Input/Output Procedures

DATE->STRING conversion specifiers