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Article contents:[[tags: egg]] == srfi-19 Time Data Types and Procedures This is a Chicken port of SRFI-19. This document describes the original SRFI API ([[http://srfi.schemers.org/srfi-19/srfi-19.html|SRFI-19]]) and the extensions (*). [[toc:]] === Abstract Points in time are represented as the number of seconds (with nanosecond precision) since "the epoch," a zero point in time. Several standard variants are defined, including UTC (universal coordinated time), TAI (international atomic time), and monotonic time. A point in time can also be represented as a Julian Day or Modified Julian Day number. Time durations, including time spent in a process or thread, are defined. Conversion routines are provided. The procedure CURRENT-TIME queries the current time in a specified variant, with a system-dependent resolution. Procedures for time arithmetic and time comparisons are also provided. A date is a representation of a point in time in the Gregorian calendar, a 24 hour clock (with nanosecond precision) and a time zone offset from UTC. Procedures for converting between time and dates are provided, as well as for reading and writing string representations of dates. === Specification A Time object, which is distinct from all existing types, defines a point in time or a time duration in some standard time system. The standard time systems are: * Universal Coordinated Time (UTC) * International Atomic Time (TAI) * monotonic time (a monotonically increasing point in time from Jan 1, 1970) * CPU time in current thread * CPU time in current process Time duration. A time object consists of three components: * Time type, a symbol representing the time system representation used. The constants {{time-tai}}, {{time-utc}}, {{time-monotonic}}, {{time-thread}}, {{time-process}}, {{and}} {{time-duration}} must be provided for these symbols. * Second, an integer representing the number of whole seconds from "the epoch." * Nanosecond, an integer of the number of nanoseconds in the fractional portion. A Date object, which is distinct from all existing types, represents a point in time as represented by the Gregorian calendar as well as by a time zone. Dates are immutable. A date consists of the following components: * Nanosecond, an integer between 0 and 999,999,999, inclusive. * Second, an integer 0 and 60, inclusive, (60 represents a leap second) * Minute, an integer between 0 and 59, inclusive, * Hour, an integer between 0 and 23, inclusive, * Day, an integer between 0 and 31, inclusive, the upper limit depending on the month and year of the point in time, * Month, an integer between 1 and 12, inclusive; in which 1 means January, 2 February, and so on. * Year, an integer representing the year. * Time zone, an integer representing the number of seconds east of GMT for this timezone. A Julian Day represents a point in time as a real number of days since -4713-11-24T12:00:00Z (midday UT on 24 November 4714 BC in the proleptic Gregorian calendar (1 January 4713 BC in the proleptic Julian calendar)). A Modified Julian Day represents a point in time as a real number of days since 1858-11-17T00:00:00Z (midnight UT on 17 November AD 1858). * Timezone (*) 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}} == Documentation === Usage * Module {{srfi-19}} '''reexports''' the ''time'', ''date'', ''timezone'', ''literal'', and ''io'' modules. <enscript language=scheme> (import srfi-19) </enscript> * Module {{srfi-19-core}} '''reexports''' the ''time'', ''date'', and ''timezone'' modules. <enscript language=scheme> (import srfi-19-core) </enscript> === Time <enscript language=scheme> (import srfi-19-time) </enscript> ==== Constants ===== time-duration <constant>(time-duration)</constant> Symbol representing Time duration. ===== time-monotonic <constant>(time-monotonic)</constant> Symbol representing monotonic time. ===== time-process <constant>(time-process)</constant> Symbol representing time spent in current process. ===== time-tai <constant>(time-tai)</constant> Symbol representing TAI time. ===== time-thread <constant>(time-thread)</constant> Symbol representing time spent in current thread. ===== time-utc <constant>(time-utc)</constant> ==== Current time and clock resolution ===== current-time <procedure>(current-time [TIME-TYPE]) -> time</procedure> Current time, of type time-type system, which defaults to TIME-UTC. ===== monotonic-time (*) ===== utc-time (*) ===== tai-time (*) ===== gc-time (*) ===== process-time (*) ===== thread-time (*) <procedure>(monotonic-time [SECS | NS SEC]) -> time</procedure> <procedure>(utc-time [SECS | NS SEC]) -> time</procedure> <procedure>(tai-time [SECS | NS SEC]) -> time</procedure> <procedure>(gc-time [SECS | NS SEC]) -> time</procedure> <procedure>(process-time [SECS | NS SEC]) -> time</procedure> <procedure>(thread-time [SECS | NS SEC]) -> time</procedure> Returns like: ; <none> : {{(current-time <time-type>)}}. ; {{SECS}} : {{(seconds->time SECS <time-type>)}}. ; {{NS SEC}} : {{(make-time <time-type> NS SEC)}}. From [[https://github.com/OpinionatedGeek/SRFI19|'''Chibi''' {{(srfi 19)}}]], with extensions. ===== time-resolution <procedure>(time-resolution [TIME-TYPE]) -> integer</procedure> Clock resolution, in nanoseconds, of the system clock of type type time-type system, which defaults to TIME-UTC. ==== Time object and accessors ===== make-time <procedure>(make-time TYPE NANOSECOND SECOND) -> time</procedure> Creates a time object. ===== make-time* (*) <procedure>(make-time* [weeks: 0] [days: 0] [hours: 0] [minutes: 0] [seconds: 0] [milliseconds: 0] [microseconds: 0] [nanoseconds: 0] [time-type: duration]) -> time</procedure> Returns a time-object of clock-type {{time-type}} where the seconds and nanoseconds values are calculated by summing the keyword arguments. ===== time? <procedure>(time? OBJECT) -> boolean</procedure> #t if object is a time object, otherwise, #f. ===== time-type <procedure>(time-type TIME) -> time-type</procedure> Time type. ===== time-nanosecond <procedure>(time-nanosecond TIME) -> integer</procedure> Time nanosecond. ===== time-second <procedure>(time-second TIME) -> integer</procedure> Time second. ===== set-time-type! <procedure>(set-time-type! TIME TIME-TYPE)</procedure> Changes time type. Note: This changes the semantics of the time object. To convert a time to another system of representation, use one of the conversion procedures. ===== set-time-nanosecond! <procedure>(set-time-nanosecond! TIME INTEGER)</procedure> Changes time nanosecond. ===== set-time-second! <procedure>(set-time-second! TIME INTEGER)</procedure> Changes time second. ===== time-hash (*) <procedure>(time-hash TIME [BOUND]) -> fixnum</procedure> Hash value for {{TIME}} within {{BOUND}}. ===== copy-time ===== time-copy (*) <procedure>(copy-time TIME) -> time2</procedure> <procedure>(time-copy TIME) -> time</procedure> Creates a new {{time}}, with the same time type, nanosecond, and second as {{TIME}}. ==== Time comparison procedures All of the time comparison procedures require the time objects to be of the same type. It is an error to use these procedures on time objects of different types. For the point-in-time measurements (e.g., TIME-TAI and TIME-UTC), the semantics are described in plain text. For durations, (e.g., TIME-DURATION, TIME-CPU, the semantics are described in parentheses. ===== time-compare (*) <procedure>(time-compare TIME1 TIME2) -> integer</procedure> Returns {{-1}}, {{0}}, or {{+1}}. ===== time-min (*) ===== time-max (*) <procedure>(time-min TIME1 [TIME2...]) -> time</procedure> <procedure>(time-max TIME1 [TIME2...]) -> time</procedure> Returns the minimum/maximum time object from {{TIME1 TIME2...}}. ===== time<=? <procedure>(time<=? TIME1 TIME2) -> boolean</procedure> #t if time1 is before or at (less than or equal to) time2, #f otherwise. ===== time<? <procedure>(time<? TIME1 TIME2) -> boolean</procedure> #t if time1 is before (less than) time2, #f otherwise. ===== time=? <procedure>(time=? TIME1 TIME2) -> boolean</procedure> #t if time1 at (equal) time2, #f otherwise. ===== time>=? <procedure>(time>=? TIME1 TIME2) -> boolean</procedure> #t if time1 is at or after (greater than or equal to) time2, #f otherwise. ===== time>? <procedure>(time>? TIME1 TIME2) -> boolean</procedure> #t if time1 is after (greater than) time2, #f otherwise. ==== Time arithmetic procedures ===== one-second-duration (*) <procedure>(one-second-duration) -> time</procedure> ===== one-nanosecond-duration (*) <procedure>(one-nanosecond-duration) -> time</procedure> ===== zero-time (*) <procedure>(zero-time [TIME-TYPE time-duration]) -> time</procedure> Returns a {{0}} valued {{time}} of {{TIME-TYPE}}. ; {{TIME-TYPE}} : {{(or time-tai time-utc time-monotonic time-thread time-process time-duration time-gc\)}} ===== time-difference ===== time-difference! <procedure>(time-difference TIME1 TIME2) -> time-duration</procedure> <procedure>(time-difference! TIME1 TIME2) -> time-duration</procedure> The TIME-DURATION between time1 and time2. It is an error if time1 and time2 are of different time types. ===== add-duration ===== add-duration! <procedure>(add-duration TIME1 TIME-DURATION) -> time</procedure> <procedure>(add-duration! TIME1 TIME-DURATION) -> time</procedure> The time resulting from adding time-duration to time1, which is a time object of the same time type as time1. ===== subtract-duration ===== subtract-duration! <procedure>(subtract-duration TIME1 TIME-DURATION) -> time</procedure> <procedure>(subtract-duration! TIME1 TIME-DURATION) -> time</procedure> The time resulting from subtracting time-duration to time1, which is a time object of the same time type as time1. ===== divide-duration (*) ===== divide-duration! (*) <procedure>(divide-duration DURATION REAL) -> time</procedure> <procedure>(divide-duration! DURATION REAL) -> time</procedure> Returns a duration, from {{DURATION}}, divided by {{REAL}}, without remainder. ===== multiply-duration (*) ===== multiply-duration! (*) <procedure>(multiply-duration DURATION REAL) -> time</procedure> <procedure>(multiply-duration! DURATION REAL) -> time</procedure> Returns a duration, from {{DURATION}}, multiplied by {{REAL}}, truncated. ===== time-negative? (*) ===== time-positve? (*) ===== time-zero? (*) <procedure>(time-negative? TIME) -> boolean</procedure> <procedure>(time-positve? TIME) -> boolean</procedure> <procedure>(time-zero? TIME) -> boolean</procedure> Is {{TIME}} negative/positive/zero? {{nonoseconds seconds}} where {{+/- -}} is negative, {{+/- +}} is positive, & {{0 0}} is zero. ===== time-abs (*) ===== time-abs! (*) <procedure>(time-abs TIME) -> time</procedure> <procedure>(time-abs! TIME) -> time</procedure> Returns the absolute time value, from {{TIME}}. ===== time-negate (*) ===== time-negate! (*) <procedure>(time-negate TIME) -> time</procedure> <procedure>(time-negate! TIME) -> time</procedure> Returns the sign inverted time value, from {{TIME}}. Only {{time-second}} participates. ==== Time Conversion (*) ===== time->seconds <procedure>(time->seconds TIME) -> real</procedure> Returns the {{TIME}} object value as a seconds value; may be fractional. ===== seconds->time <procedure>(seconds->time SECONDS [TIME-TYPE time-duration]) -> time</procedure> Converts a {{SECONDS}} value, may be fractional, into a {{TIME-TYPE}} time object. ===== time->nanoseconds <procedure>(time->nanoseconds TIME) -> integer</procedure> Returns the {{TIME}} object value as a nanoseconds value. ===== nanoseconds->time <procedure>(nanoseconds->time NANOSECONDS [TIME-TYPE time-duration]) -> time</procedure> Returns the {{NANOSECONDS}} value as a time {{TIME-TYPE}} object. ===== nanoseconds->seconds <procedure>(nanoseconds->seconds NANOSECONDS) -> real</procedure> Returns the {{NANOSECONDS}} value as a seconds value. ===== time->milliseconds <procedure>(time->milliseconds TIME) -> integer</procedure> Returns the {{TIME}} object value as a milliseconds value. ===== milliseconds->time <procedure>(milliseconds->time MILLISECONDS [TIME-TYPE time-duration]) -> time</procedure> Returns the {{MILLISECONDS}} value as a time {{TIME-TYPE}} object. ===== milliseconds->seconds <procedure>(milliseconds->seconds MILLISECONDS) -> real</procedure> Returns the {{MILLISECONDS}} value as a seconds value. ==== 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) -> srfi-18#time</procedure> 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) -> srfi-19#time</procedure> Converts a SRFI-18 time object into a SRFI-19 {{time-duration}} object. === Date <enscript language=scheme> (import srfi-19-date) </enscript> === Types {{TIMEZONE-INFO}} is a {{tz-offset}}, a {{boolean}} where {{#t}} is {{(local-timezone-locale)}} & {{#f}} is {{(utc-timezone-locale)}}, or a {{timezone-components}}. ==== Current date ===== current-date <procedure>(current-date [TZ-OFFSET]) -> date</procedure> Date corresponding to the current UTC time. ===== current-julian-day <procedure>(current-julian-day) -> real</procedure> Current Julian Day. ===== current-modified-julian-day <procedure>(current-modified-julian-day) -> real</procedure> Current Modified Julian Day. ==== Date object and accessors Date objects are immutable once created. ===== default-date-clock-type <parameter>(default-date-clock-type [CLOCK-TYPE time-utc]) -> symbol</parameter> Sets or gets the clock-type used by default for conversion of a date to a time. ===== make-date (extended) <procedure>(make-date NANOSECOND SECOND MINUTE HOUR DAY MONTH YEAR [ZONE-OFFSET [TZ-NAME [DST-FLAG]]]) -> date</procedure> 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. ===== copy-date (*) ===== date-copy (*) <procedure>(copy-date DATE) -> date</procedure> <procedure>(date-copy DATE) -> date</procedure> Returns an exact copy of the specified {{DATE}} object. ===== date? <procedure>(date? DATE) -> boolean</procedure> #t if object is a time object, otherwise, #f. ===== date-nanosecond <procedure>(date-nanosecond DATE) -> integer</procedure> Date nanosecond. ===== date-second <procedure>(date-second DATE) -> integer</procedure> Date second. ===== date-minute <procedure>(date-minute DATE) -> integer</procedure> Date minute. ===== date-hour <procedure>(date-hour DATE) -> integer</procedure> Date hour. ===== date-day <procedure>(date-day DATE) -> integer</procedure> Date day. ===== date-month <procedure>(date-month DATE) -> integer</procedure> Date month. ===== date-year <procedure>(date-year DATE) -> integer</procedure> Date year. ===== date-zone-offset <procedure>(date-zone-offset DATE) -> integer</procedure> Date time zone offset. ===== date-zone-name (*) <procedure>(date-zone-name DATE) -> boolean</procedure> <procedure>(date-zone-name DATE) -> string</procedure> Returns the timezone abbreviation of the specified {{DATE}} object. The result is either a string or {{#f}}. ===== date-dst? (*) <procedure>(date-dst? DATE) -> boolean</procedure> 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-year-day <procedure>(date-year-day DATE) -> integer</procedure> The ordinal day of the year of this date. January 1 is 1, etc. ===== date-week-day <procedure>(date-week-day DATE) -> integer</procedure> The day of the week of this date, where Sunday=0, Monday=1, etc. ===== date-week-number <procedure>(date-week-number DATE DAY-OF-WEEK-STARTING-WEEK) -> integer</procedure> The ordinal week of the year which holds this date, ignoring a first partial week. 'Day-of-week-starting-week' is the integer corresponding to the day of the week which is to be considered the first day of the week (Sunday=0, Monday=1, etc.). ===== leap-year? (*) <procedure>(leap-year? YEAR) -> boolean</procedure> Is the specified {{YEAR}} a leap year? ; {{YEAR}} : {{(or fixnum date)}} ; numeric year or {{date}} object. ===== leap-day? (*) <procedure>(leap-day? DATE) -> boolean</procedure> Is the specified {{DATE}} a leap day? The leap day of the leap month of a leap year. ==== Time/Date/Julian Day/Modified Julian Day Converters ===== seconds->date <procedure>(seconds->date SECONDS [TZ-OFFSET #t]) -> date</procedure> Converts a {{SECONDS}} value, which may be fractional, into a date object. {{SECONDS}} is relative to 00:00:00 January 1, 1970 UTC. ===== date->seconds (*) <procedure>(date->seconds DATE [CLOCK-TYPE (default-date-clock-type)]) -> real</procedure> 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. ===== time->date <procedure>(time->date TIME) -> date</procedure> Returns the {{TIME}} object value as a date. A shorthand for the {{(time-*->date...)}} procedures. ===== date->time (*) <procedure>(date->time DATE [CLOCK-TYPE (default-date-clock-type)]) -> time</procedure> Returns the specified {{DATE}} as a time-object of type {{CLOCK-TYPE}}. ===== date->julian-day <procedure>(date->julian-day DATE) -> jd</procedure> Convert date to Julian Day. ===== date->modified-julian-day <procedure>(date->modified-julian-day DATE) -> mjd</procedure> Convert date to Modified Julian Day. ===== date->time-monotonic <procedure>(date->time-monotonic DATE) -> time-monotonic</procedure> Convert date to monotonic time. ===== date->time-tai <procedure>(date->time-tai DATE) -> time-tai</procedure> Convert date to TAI time. ===== date->time-utc <procedure>(date->time-utc DATE) -> time-utc</procedure> Convert date to UTC time. ===== time->julian-day <procedure>(time->julian-day TIME) -> real</procedure> Returns the julian day for the {{TIME}} object. ===== julian-day->date <procedure>(julian-day->date JD [TZ-OFFSET]) -> date</procedure> Convert Julian Day to date, , using time zone offset, which defaults to the local time zone. ===== julian-day->time-monotonic <procedure>(julian-day->time-monotonic JD) -> time-monotonic</procedure> Convert Julian Day to monotonic time. ===== julian-day->time-tai <procedure>(julian-day->time-tai JD) -> time-tai</procedure> Convert Julian Day to TAI time. ===== julian-day->time-utc <procedure>(julian-day->time-utc JD) -> time-utc</procedure> Convert Julian Day to UTC time. ===== time->modified-julian-day <procedure>(time->modified-julian-day TIME) -> real</procedure> Returns the modified julian day for the {{TIME}} object. ===== modified-julian-day->date <procedure>(modified-julian-day->date MJD [TZ-OFFSET]) -> date</procedure> Convert Modified Julian Day to date, using time zone offset, which defaults to the local time zone. ===== modified-julian-day->time-monotonic <procedure>(modified-julian-day->time-monotonic MJD) -> time-monotonic</procedure> Convert Modified Julian Day to monotonic time. ===== modified-julian-day->time-tai <procedure>(modified-julian-day->time-tai MJD) -> time-tai</procedure> Convert Modified Julian Day to TAI time. ===== modified-julian-day->time-utc <procedure>(modified-julian-day->time-utc MJD) -> time-utc</procedure> Convert Modified Julian Day to UTC time. ===== time-monotonic->date <procedure>(time-monotonic->date TIME-MONOTONIC [TZ-OFFSET]) -> date</procedure> Convert monotonic time to date, using time zone offset, which defaults to the local time zone. ===== time-monotonic->julian-day <procedure>(time-monotonic->julian-day TIME-MONOTONIC) -> jd</procedure> Convert monotonic time to Julian Day. ===== time-monotonic->modified-julian-day <procedure>(time-monotonic->modified-julian-day TIME-MONOTONIC) -> mjd</procedure> Convert monotonic time to Modified Julian Day. ===== time-monotonic->time-tai <procedure>(time-monotonic->time-tai TIME-MONOTONIC) -> time-tai</procedure> Convert monotonic time to TAI time. ===== time-monotonic->time-tai! <procedure>(time-monotonic->time-tai! TIME-MONOTONIC) -> time-tai</procedure> Convert monotonic time to TAI time. The time structure may be reused. ===== time-monotonic->time-utc <procedure>(time-monotonic->time-utc TIME-MONOTONIC) -> time-utc</procedure> Convert monotonic time to UTC time. ===== time-monotonic->time-utc! <procedure>(time-monotonic->time-utc! TIME-MONOTONIC) -> time-utc</procedure> Convert monotonic time to UTC time. The time structure may be reused. ===== time-tai->date <procedure>(time-tai->date TIME-TAI [TZ-OFFSET]) -> date</procedure> Convert TAI time to date, using time zone offset, which defaults to the local time zone. ===== time-tai->julian-day <procedure>(time-tai->julian-day TIME-TAI) -> jd</procedure> Convert TAI time to Julian Day. ===== time-tai->modified-julian-day <procedure>(time-tai->modified-julian-day TIME-TAI) -> mjd</procedure> Convert TAI time to Modified Julian Day. ===== time-tai->time-monotonic <procedure>(time-tai->time-monotonic TIME-TAI) -> time-monotonic</procedure> Convert TAI time to monotonic time. ===== time-tai->time-monotonic! <procedure>(time-tai->time-monotonic! TIME-TAI) -> time-monotonic</procedure> Convert TAI time to monotonic time. The time structure may be reused. ===== time-tai->time-utc <procedure>(time-tai->time-utc TIME-TAI) -> time-utc</procedure> Convert TAI time to monotonic time. ===== time-tai->time-utc! <procedure>(time-tai->time-utc! TIME-TAI) -> time-utc</procedure> Convert TAI time to monotonic time. The time structure may be reused. ===== time-utc->date <procedure>(time-utc->date TIME-UTC [TZ-OFFSET]) -> time-utc</procedure> Convert UTC time to date, using time zone offset, which defaults to the local time zone. ===== time-utc->julian-day <procedure>(time-utc->julian-day TIME-UTC) -> jd</procedure> Convert UTC time to Julian Day ===== time-utc->modified-julian-day <procedure>(time-utc->modified-julian-day TIME-UTC) -> mjd</procedure> Convert UTC time to Modified Julian Day. ===== time-utc->time-monotonic <procedure>(time-utc->time-monotonic TIME-UTC) -> time-monotonic</procedure> Convert UTC time to monotonic time. ===== time-utc->time-monotonic! <procedure>(time-utc->time-monotonic! TIME-UTC) -> time-monotonic</procedure> Convert UTC time to monotonic time. The time structure may be reused. ===== time-utc->time-tai <procedure>(time-utc->time-tai TIME-UTC) -> time-tai</procedure> Convert UTC time to TAI time. ===== time-utc->time-tai! <procedure>(time-utc->time-tai! TIME-UTC) -> time-tai</procedure> Convert UTC time to TAI time. The time structure may be reused. ==== Date Arithmetic (*) ===== date-difference <procedure>(date-difference DATE1 DATE2 [CLOCK-TYPE]) -> time</procedure> Returns the {{time-duration}} between {{DATE1}} and {{DATE2}}. ===== date-add-duration <procedure>(date-add-duration DATE DURATION [CLOCK-TYPE]) -> date</procedure> Returns a new date, the {{DATE}} plus the {{DURATION}}. ===== date-subtract-duration <procedure>(date-subtract-duration DATE DURATION [CLOCK-TYPE]) -> date</procedure> Returns a new date, the {{DATE}} minus the {{DURATION}}. ===== date-adjust <procedure>(date-adjust DATE AMOUNT KEY [CLOCK-TYPE]) -> date</procedure> 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]) -> date</procedure> 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 convenience wrapper of {{date-adjust}}. ==== Date Comparison (*) ===== date-compare <procedure>(date-compare DATE1 DATE2) -> integer</procedure> Returns {{-1}}, {{0}}, or {{+1}}. ===== date-hash <procedure>(date-hash DATE [BOUND]) -> fixnum</procedure> Hash value for {{DATE}} within {{BOUND}}. ===== date=? <procedure>(date=? DATE1 DATE2) -> boolean</procedure> Is {{DATE1}} on {{DATE2}}? ===== date>? <procedure>(date>? DATE1 DATE2) -> boolean</procedure> Is {{DATE1}} after {{DATE2}}? ===== date<? <procedure>(date<? DATE1 DATE2) -> boolean</procedure> Is {{DATE1}} before {{DATE2}}? ===== date>=? <procedure>(date>=? DATE1 DATE2) -> boolean</procedure> Is {{DATE1}} after or on {{DATE2}}? ===== date<=? <procedure>(date<=? DATE1 DATE2) -> boolean</procedure> Is {{DATE1}} before or on {{DATE2}}? ===== read-leap-second-table <procedure>(read-leap-second-table FILENAME)</procedure> 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. === Timezone (*) The daylight saving time (summer time) flag is '''always''' taken from the system ([[locale]] egg) 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. <enscript language=scheme> (import srfi-19-timezone) </enscript> ==== local-timezone-locale <parameter>(local-timezone-locale [TZ-COMPONENTS])</parameter> Gets or sets the local timezone-locale object. ==== utc-timezone-locale <parameter>(utc-timezone-locale [TZ-COMPONENTS])</parameter> 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]) -> symbol</procedure> 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]) -> integer</procedure> 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]) -> boolean</procedure> Returns the timezone-locale daylight saving time flag of the supplied {{TZ-COMPONENTS}}, or the {{(local-timezone-locale)}} if missing. === Date to String/String to Date Converters (Input/Output Procedures) <enscript language=scheme> (import srfi-19-io) </enscript> ==== format-date (*) <procedure>(format-date DESTINATION DATE-FORMAT DATE)</procedure> <procedure>(format-date DATE-FORMAT DATE) -> {{string}}</procedure> 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) -> date</procedure> 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}}. ==== date->string <procedure>(date->string DATE [DATE-FORMAT]) -> date</procedure> ; {{DATE}} : {{date}} ; {{DATE-FORMAT}} : {{string}} ; default {{"~c"}}. ==== string->date <procedure>(string->date SOURCE [TEMPLATE]) -> date</procedure> ; {{SOURCE}} : see {{scan-date}}. ; {{TEMPLATE}} : {{string}} ; default {{(localized-template/default 'srfi-19 'date-time)}}. 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. ==== DATE->STRING conversion specifiers * Conversion specifier form : {{~[-_][fHIjmMNSy]}} <table> <tr><th>Ch</th><th>Conversion</th></tr> <tr><td>~~</td><td>a literal ~</td></tr> <tr><td>~a</td><td>locale's abbreviated weekday name (Sun...Sat)</td></tr> <tr><td>~A</td><td>locale's full weekday name (Sunday...Saturday)</td></tr> <tr><td>~b</td><td>locale's abbreviate month name (Jan...Dec)</td></tr> <tr><td>~B</td><td>locale's full month day (January...December)</td></tr> <tr><td>~c</td><td>locale's date and time (e.g., "Fri Jul 14 20:28:42-0400 2000")</td></tr> <tr><td>~d</td><td>day of month, zero padded (01...31)</td></tr> <tr><td>~D</td><td>date (mm/dd/yy)</td></tr> <tr><td>~e</td><td>day of month, blank padded ( 1...31)</td></tr> <tr><td>~f</td><td>seconds+fractional seconds, using locale's decimal separator (e.g. 5.2).</td></tr> <tr><td>~g</td><td>day of month</td></tr> <tr><td>~h</td><td>same as ~b</td></tr> <tr><td>~H</td><td>hour, zero padded, 24-hour clock (00...23)</td></tr> <tr><td>~I</td><td>hour, zero padded, 12-hour clock (01...12)</td></tr> <tr><td>~j</td><td>day of year, zero padded</td></tr> <tr><td>~k</td><td>hour, blank padded, 24-hour clock ( 0...23)</td></tr> <tr><td>~l</td><td>hour, blank padded, 12-hour clock ( 1...12)</td></tr> <tr><td>~m</td><td>month, zero padded (01...12)</td></tr> <tr><td>~M</td><td>minute, zero padded (00...59)</td></tr> <tr><td>~n</td><td>new line</td></tr> <tr><td>~N</td><td>nanosecond, zero padded</td></tr> <tr><td>~p</td><td>locale's AM or PM</td></tr> <tr><td>~r</td><td>time, 12 hour clock, same as "~I:~M:~S ~p"</td></tr> <tr><td>~s</td><td>number of full seconds since "the epoch" (in UTC)</td></tr> <tr><td>~S</td><td>second, zero padded (00...60)</td></tr> <tr><td>~t</td><td>horizontal tab</td></tr> <tr><td>~T</td><td>time, 24 hour clock, same as "~H:~M:~S"</td></tr> <tr><td>~u</td><td>day ordinal suffix</td></tr> <tr><td>~U</td><td>week number of year with Sunday as first day of week (00...53)</td></tr> <tr><td>~V</td><td>ISO 8601 week number of the year with Monday as first day of week (01..53)</td></tr> <tr><td>~w</td><td>day of week (0...6)</td></tr> <tr><td>~W</td><td>week number of year with Monday as first day of week (01...52)</td></tr> <tr><td>~x</td><td>locale's date representation</td></tr> <tr><td>~X</td><td>locale's time representation</td></tr> <tr><td>~y</td><td>last two digits of year (00...99)</td></tr> <tr><td>~Y</td><td>4-digit year</td></tr> <tr><td>~z</td><td>time zone in RFC-822 style</td></tr> <tr><td>~Z</td><td>symbol time zone (not-implemented)</td></tr> <tr><td>~1</td><td>ISO-8601 year-month-day format</td></tr> <tr><td>~2</td><td>ISO-8601 hour-minute-second-timezone format</td></tr> <tr><td>~3</td><td>ISO-8601 hour-minute-second format</td></tr> <tr><td>~4</td><td>ISO-8601 year-month-day-hour-minute-second-timezone format</td></tr> <tr><td>~5</td><td>ISO-8601 year-month-day-hour-minute-second format</td></tr> </table> The normally zero-padded conversions {{f}}, {{H}}, {{I}}, {{j}}, {{m}}, {{M}}, {{N}}, {{S}}, {{y}} have a padding character override feature. If the tilde is followed by a {{-}} then padding is suppressed. If followed by a {{_}} the space character is used for padding. Otherwise, the default, zero-padding is perfomed. * {{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. {{g}} & {{u}} from [[https://github.com/OpinionatedGeek/SRFI19|'''Chibi''' {{(srfi 19)}}]]. ==== STRING->DATE conversion specifiers <table> <tr><th>Ch</th><th>Skip to</th><th>Read</th><th>Set</th></tr> <tr><td>~~</td><td>any</td><td>read literal</td><td>~</td></tr> <tr><td>~a</td><td>char-alphabetic?</td><td>abbreviated weekday in locale</td><td>nothing</td></tr> <tr><td>~A</td><td>char-alphabetic?</td><td>full weekday in locale</td><td>nothing</td></tr> <tr><td>~b</td><td>char-alphabetic?</td><td>abbreviated month name in locale</td><td>nothing</td></tr> <tr><td>~B</td><td>char-alphabetic?</td><td>full month name in locale</td><td>nothing</td></tr> <tr><td>~d</td><td>char-numeric?</td><td>day of month</td><td>date-day</td></tr> <tr><td>~e</td><td>any</td><td>day of month, blank padded</td><td>date-day</td></tr> <tr><td>~f</td><td>char-decimal?</td><td>seconds+fractional seconds, using locale's decimal separator (e.g. 5.2).</td><td>date-second+date-nanosecond</td></tr> <tr><td>~h</td><td>char-alphabetic?</td><td>same as ~b</td><td>nothing</td></tr> <tr><td>~H</td><td>char-numeric?</td><td>hour</td><td>date-hour</td></tr> <tr><td>~k</td><td>any</td><td>hour, blank padded</td><td>date-hour</td></tr> <tr><td>~m</td><td>char-numeric?</td><td>month</td><td>date-month</td></tr> <tr><td>~M</td><td>char-numeric?</td><td>minute</td><td>date-minute</td></tr> <tr><td>~S</td><td>char-numeric?</td><td>second</td><td>date-second</td></tr> <tr><td>~y</td><td>any</td><td>2-digit year</td><td>date-year within 50 years</td></tr> <tr><td>~Y</td><td>char-signed-numeric?</td><td>4-digit year</td><td>date-year</td></tr> <tr><td>~z</td><td>any</td><td>time zone</td><td>date-zone-offset</td></tr> </table> === Date/Time Literals (*) Literal Date/Time forms. ==== Usage <enscript language=scheme> (import srfi-19-literals) </enscript> ===== date-literal-form <parameter>(date-literal-form [FORM]) -> (or boolean symbol)</parameter> The {{date}} literal format. ; {{#f}} : #<srfi-19#date ...> ; {{SRFI-10}} : #,(srfi-19-date ...) ; {{#t}} : #@... ; the default ; {{|#@|}} : #@... ===== time-literal-form <parameter>(time-literal-form [FORM]) -> (or boolean symbol)</parameter> 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]) -> list</procedure> 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:~f~z"}} : date time timezone ; {{"~Y-~m-~dT~H:~M:~f"}} : date time ; {{"~Y-~m-~d"}} : date ; {{"~H:~M:~f~z"}} : time timezone; {{date}} components from {{(current-date)}} ; {{"~H:~M:~f"}} : time; {{date}} components from {{(current-date)}} ===== write-date-literal <procedure>(write-date-literal DATE [PORT])</procedure> Write the {{DATE}} to the {{PORT}} using a string ISO form; {{"~Y-~m-~dT~H:~M:~f~z"}}. ; {{PORT}} : {{output-port}} ; default {{(current-output-port)}} === Time Period (*) A time-period is an interval, [begin end), where begin and end are time objects of the same clock type. ==== Usage <enscript language=scheme> (import srfi-19-period) </enscript> ===== make-time-period <procedure>(make-time-period BEGIN END [CLOCK-TYPE (default-date-clock-type)]) -> time-period</procedure> 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) -> time-period</procedure> Returns a copy of {{TIME-PERIOD}}. ===== time-period-begin <procedure>(time-period-begin TIME-PERIOD)</procedure> Returns the start time for the {{TIME-PERIOD}}. ===== time-period-end <procedure>(time-period-end TIME-PERIOD) -> time</procedure> Returns the end time for the {{TIME-PERIOD}}. ===== time-period-last <procedure>(time-period-last TIME-PERIOD) -> time</procedure> Returns the last time for the {{TIME-PERIOD}}; {{(time-period-end - TIME-FINE-GRAIN)}}. ===== time-period-type <procedure>(time-period-type TIME-PERIOD) -> symbol</procedure> Returns the clock-type of the {{TIME-PERIOD}}. ===== time-period? <procedure>(time-period? OBJECT) -> boolean</procedure> Is {{OBJECT}} a time-period? ===== time-period-duration <procedure>(time-period-duration TIME-PERIOD) -> time</procedure> Returns the time-duration of the {{TIME-PERIOD}}. ===== time-period-hash <procedure>(time-period-hash TIME-PERIOD [BOUND]) -> fixnum</procedure> Hash value for {{TIME-PERIOD}} within {{BOUND}}. ===== time-period-compare <procedure>(time-period-compare TIME-PERIOD-1 TIME-PERIOD-2) -> integer</procedure> Returns {{-1}}, {{0}}, or {{+1}}. ===== time-period=? <procedure>(time-period=? TIME-PERIOD-1 TIME-PERIOD-2) -> boolean</procedure> Does {{TIME-PERIOD-1}} begin & end with {{TIME-PERIOD-2}}? ===== time-period<? <procedure>(time-period<? TIME-PERIOD-1 TIME-PERIOD-2) -> boolean</procedure> Does {{TIME-PERIOD-1}} end before {{TIME-PERIOD-2}} begins? ===== time-period>? <procedure>(time-period>? TIME-PERIOD-1 TIME-PERIOD-2) -> boolean</procedure> Does {{TIME-PERIOD-1}} begin after {{TIME-PERIOD-2}} ends? ===== time-period<=? <procedure>(time-period<=? TIME-PERIOD-1 TIME-PERIOD-2) -> boolean</procedure> Does {{TIME-PERIOD-1}} end on or before {{TIME-PERIOD-2}} begins? ===== time-period>=? <procedure>(time-period>=? TIME-PERIOD-1 TIME-PERIOD-2) -> boolean</procedure> Does {{TIME-PERIOD-1}} begin on or after {{TIME-PERIOD-2}} ends? ===== time-period-precedes? ===== time-period-meets? ===== time-period-overlaps? ===== time-period-finished-by? ===== time-period-contains? ===== time-period-starts? ===== time-period-equals? ===== time-period-started-by? ===== time-period-during? ===== time-period-finishes? ===== time-period-overlapped-by? ===== time-period-met-by? ===== time-period-preceded-by? <procedure>(time-period-precedes? TIME-PERIOD-1 TIME-PERIOD-2) -> boolean</procedure> <procedure>(time-period-meets? TIME-PERIOD-1 TIME-PERIOD-2) -> boolean</procedure> <procedure>(time-period-overlaps? TIME-PERIOD-1 TIME-PERIOD-2) -> boolean</procedure> <procedure>(time-period-finished-by? TIME-PERIOD-1 TIME-PERIOD-2) -> boolean</procedure> <procedure>(time-period-contains? TIME-PERIOD-1 TIME-PERIOD-2) -> boolean</procedure> <procedure>(time-period-starts? TIME-PERIOD-1 TIME-PERIOD-2) -> boolean</procedure> <procedure>(time-period-equals? TIME-PERIOD-1 TIME-PERIOD-2) -> boolean</procedure> <procedure>(time-period-started-by? TIME-PERIOD-1 TIME-PERIOD-2) -> boolean</procedure> <procedure>(time-period-during? TIME-PERIOD-1 TIME-PERIOD-2) -> boolean</procedure> <procedure>(time-period-finishes? TIME-PERIOD-1 TIME-PERIOD-2) -> boolean</procedure> <procedure>(time-period-overlapped-by? TIME-PERIOD-1 TIME-PERIOD-2) -> boolean</procedure> <procedure>(time-period-met-by? TIME-PERIOD-1 TIME-PERIOD-2) -> boolean</procedure> <procedure>(time-period-preceded-by? TIME-PERIOD-1 TIME-PERIOD-2) -> boolean</procedure> Returns the relationship per [[https://ics.uci.edu/~alspaugh/cls/shr/allen.html|''Allen's Interval Algebra'']]. ===== time-period-preceding <procedure>(time-period-preceding TIME-PERIOD-1 TIME-PERIOD-2) -> (or false time-period)</procedure> 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) -> (or false time-period)</procedure> 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) -> boolean</procedure> Is {{TIME-PERIOD-2}} within {{TIME-PERIOD-1}}? ===== time-period-contains/time? <procedure>(time-period-contains/time? TIME-PERIOD TIME) -> boolean</procedure> 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) -> boolean</procedure> Is {{DATE}} within {{TIME-PERIOD}}? {{DATE}} is converted to a compatible time if possible. ===== time-period-contains? <procedure>(time-period-contains? TIME-PERIOD OBJECT) -> boolean</procedure> 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) -> boolean</procedure> Does {{TIME-PERIOD-2}} overlap {{TIME-PERIOD-1}}? ===== time-period-intersection <procedure>(time-period-intersection TIME-PERIOD-1 TIME-PERIOD-2) -> (or false time-period)</procedure> 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) -> (or false time-period)</procedure> 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) -> time-period</procedure> 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) -> time-period</procedure> Returns a copy of {{TIME-PERIOD}} shifted by {{DURATION}}. ===== time-period-shift! <procedure>(time-period-shift! TIME-PERIOD DURATION) -> time-period</procedure> Returns {{TIME-PERIOD}} shifted by {{DURATION}}. == SRFI 29 bundles * Installed w/ the egg are: ; {{en}} : English (American) - only shipping {{u}} support at the moment ; {{de}} : German ; {{it}} : Italian ; {{es}} : Spanish ; {{nl}} : Dutch ; {{pt_br}} : Brazilian Portuguese Default bundle is {{en}}. == Examples * Prevent default timezone initialization by explicitly setting the 'timezone. <enscript language=scheme> ;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)) </enscript> * Provide {{SRFI-128}} {{comparators}}. <enscript language=scheme> (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)) (make-comparator srfi-19-period time-period? time-period=? time-period<? time-period-hash) ) </enscript> == 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 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 -9999..9999 properly. The ISO 8601 year convention for 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. <enscript language=javascript> 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 </enscript> 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|SRFI 29 bundles]] for {{u}} conversion support. == Requirements [[utf8]] [[srfi-1]] [[srfi-18]] [[srfi-29]] [[miscmacros]] [[locale]] [[record-variants]] [[check-errors]] * Test Only [[Test]] [[test-utils]] [[format]] == Author [[/users/kon-lovett|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|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 [[/egg-svn-checkout|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 ; 4.10.2 : Fix {{seconds->date}} optional {{timezone-info}}. ; 4.10.1 : Fix signatures (again). ; 4.10.0 : Extend {{<time-type>-time}} functions. Fix signatures. ; 4.9.11 : Remove useless signatures (bug reported by shawnw on #chicken irc). ; 4.9.10 : Add {{make-time*}}, deprecate {{make-duration}}, fix signatures. ; 4.9.9 : Read BCE (full) years (~Y). ; 4.9.8 : Fix parameters error on bad argument. ; 4.9.7 : Add {{~f}} input conversion. Fix {{time-period-compare}}. ; 4.9.6 : Register the feature. Add {{leap-day?}}. ; 4.9.5 : Remove code/data duplicates. ; 4.9.4 : Restore {{copy-time}} & add {{copy-date}}. ; 4.9.3 : Fix {{*-hash}} range test. ; 4.9.2 : Fix {{time-hash}} result bounds. ; 4.9.1 : Fix {{date-adjust}} synonym lookup. ; 4.9.0 : SRFI-69 conforming {{date-hash}}, {{time-hash}}, & {{period-hash}}. Drop [[srfi-69]] dependency. ; 4.8.2 : Fix {{~V}}. ; 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 Copyright (C) 2009-2024 Kon Lovett. All rights reserved. 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. THE SOFTWARE IS PROVIDED ASIS, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. Copyright (C) I/NET, Inc. (2000, 2002, 2003). All Rights Reserved. Copyright (C) Neodesic Corporation (2000). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. 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