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*To*: <srfi-19@xxxxxxxxxxxxxxxxx>*Subject*: new time and date procedures*From*: "Will Fitzgerald" <fitzgerald@xxxxxxxxxxxx>*Date*: Wed, 5 Apr 2000 10:43:10 -0400*Importance*: Normal*In-reply-to*: <200003141532.KAA06567@xxxxxxxxxxxxxxxxxxxxx>*Reply-to*: <fitzgerald@xxxxxxxxxxxx>

Taking the comments so far, I'd like to suggest changing the time and date procedures in the following way. This isn't a complete write-up, and I haven't done the implementation, but I'd be glad for your opinions: ;; data types time : structured record second/minute/hour/day/month/year/day of week/ day of year/daylights savings time/time zone offset. Equivalent to universal time. Implementations can vary as to whether leap are included. Range is implementation specific. seconds : real, potentially inexact, corresponding to the number of seconds from 0 to implementation specific upper range. What '0' corresponds to in the real world is also implementation specific. Julian day number : integer, corresponding to the number of days from 0 to implementation specific upper range. What '0' corresponds to in the real world is also implementation specific. Implementations should describe the ranges of these numbers and their correspondence with the real world. ;; get the current values (current-time) (current-julian-day-number) ; '0' is implementation specific (current-seconds) ; '0' is implementation specific. ; convertible to time. (current-process-seconds) ; '0' and value is implantation specific (current-run-seconds) ; '0' and value is implementation specific Note: process-seconds and run-seconds don't have the same 0 as (current-seconds) seconds. ;; readers ; TIME (time-second time) => real (0 to 61.0) ; potentially includes leap seconds (time-minute time) => integer (0 to 59) (time-hour time) => integer (0 to 23) (time-day time) => integer (1 to 31) (time-month time) => integer (1 to 12) (January=1, etc.) (time-year time) => integer (time-week-day) => integer (0 to 6) (Sunday=0 to Saturday=6). (time-year-day) => integer (0 to 365) (time-dst? time) => boolean (#t if observing dst, #f otherwise) (time-zone-offset time) => integer ; JULIAN-DAY-NUMBER (julian-day-number-day jdn) => integer (1 to 31) (julian-day-number-month jdn) => integer (1 to 12) (julian-day-number-year jdn) => integer ;; encoders (make-time second minute hour date month year) (make-time second minute hour date month year zone-offset) (make-julian-day-number day month year) ;; writers (set-time-second! time real) (set-time-minute! time integer) (set-time-hour! time integer) (set-time-day! time integer) (set-time-month! time integer) (set-time-year! time integer) (set-time-dst?! time boolean) (set-time-zone-offset! time integer) ;; converters. all strings are ISO formats. (time->seconds time) => real (seconds->time real) => time (time->julian-day-number time) => integer (julian-day-number->time integer) => time (julian-day-number->seconds integer) => real (seconds->julian-day-number real) => integer (time->string time) => string (string->time string) => time (julian-day-number->string integer) => string (string->julian-day-number string) => integer (seconds->string seconds) => string (string->seconds string) => real ;; comparing procedures (time=? time1 time2) => boolean (time>? time1 time2) => boolean (time<? time1 time2) => boolean (time>=? time1 time2) => boolean (time<=? time1 time2) => boolean ;; data type probes (time? time) => boolean

**References**:**Re: leap seconds***From:*Marc Feeley

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