Files
el/tests/calendar/examples/cycle-300yr.el
Will Anderson ed564b6dda add Calendar + CalendarTime + Rhythm + LocalDate/Time as first-class
Phase 1.5 of time-system. Calendar is pluggable: EarthCalendar
(IANA zones, DST, Gregorian) is the default; MarsCalendar,
CycleCalendar(period), NoCycleCalendar handle non-Earth cases.

Rhythm abstracts recurrence from clock units - rhythm_cycle_phase(0.5)
means "midpoint of cycle" whether the cycle is 24 hours on Earth or
30 hours on a station or 300 years on a long-cycle world.

Phase 1 (Instant + Duration) unchanged. EarthCalendar(zone_local())
is the user-facing default; nobody who doesn't care about non-Earth
calendars sees the abstraction.

Self-host fixed point holds at 6339 lines.
Snapshot tagged at dist/platform/elc.20260502-1321-self-host.

Phase 2 (scheduling primitives every/after/at) lands next, now with
Calendar-aware grounding instead of Earth-time hardcoded.

Backlog: bl-297f66d8 (supersedes bl-b29b3e60)
2026-05-02 13:21:43 -05:00

24 lines
915 B
EmacsLisp

// cycle-300yr.el CycleCalendar with a 100-year period proves the math
// holds at long periods. (300 years exceeds int64 nanos: 2^63 ns 292 yr;
// 100 yr is the largest round period that fits while leaving headroom for
// instants on either side.) One earth year apart yields phase_diff ~ 0.01.
fn run_test() -> String {
// 100 Julian years = 100 * 31557600 = 3155760000 seconds.
let period: Duration = duration_seconds(3155760000)
let cal: Calendar = cycle_calendar(period)
let base: Instant = unix_seconds(0)
let later: Instant = unix_seconds(31557600)
let ct1: CalendarTime = in_calendar(base, cal)
let ct2: CalendarTime = in_calendar(later, cal)
let p1: Float = cal_cycle_phase(ct1)
let p2: Float = cal_cycle_phase(ct2)
let diff: Float = p2 - p1
// 1 year / 100 years = 0.01
return format_float(diff, 2)
}
fn main() -> Void {
println(run_test())
}