module std.time

std.time — time, calendar and clocks (§17). Decisions D-3100..D-3119.

The builtin types live in std.core (the prelude): Duration (i64 ns), Time (UTC instant, i64 ns since the epoch), Instant (monotonic), Date (days since the epoch), LocalDateTime (wall clock without a zone, i64 ns), Tz (zone name) and Cron. This module adds the methods, TimeOfDay, ZonedTime, Period, schedules and timers. The public aliases make the types importable as use std.time { Duration } (D-810). Inside this module the private aliases Dur, Inst, Tm, Ldt are used so that the public aliases stay "unused" until a program uses them.

Calendar arithmetic, formatting, parsing, cron and the zone database are in the runtime (runtime/src/timelib), the zones come from the system tz database (D-3104). Patterns: yyyy yy MMMM MMM MM M dd d EEEE EEE HH H hh h a mm m ss s S.. XXX XX X z VV, text in single quotes (D-3103).

Example:

oxl✓ checked in CI

use std.time { Time }

fn main() io {
  let start = 2026-11-03T18:00
  let meeting = (start + 90m).in(tz"Europe/Berlin")!
  print("{meeting.toIso()} {(2026-01-31 + 1.month()).toIso()}")
}

Output

2026-11-03T19:30:00+01:00[Europe/Berlin] 2026-02-28

Types

enum `Ambiguity`	Which of two equal wall-clock times to take when clocks are set back (§17.2)
data `AmbiguousTime`	A local wall-clock time that occurs twice (clocks set back) and Ambiguity.Reject was requested (§17.2).
type `Cron`	A cron expression (the type is declared in the prelude; literal cron"0 9 MON-FRI").
type `Date`	A calendar date (the type is declared in the prelude; literal 2026-11-03).
type `Dur`	type alias · std.time
type `Duration`	An exact time interval in nanoseconds (the type is declared in the prelude; use std.time { Duration } imports it with its methods).
type `i64`	type alias · std.time
type `Inst`	type alias · std.time
type `Instant`	A reading of the monotonic clock, for measuring intervals (the type is declared in the prelude).
type `Ldt`	type alias · std.time
type `LocalDateTime`	A date and time without a time zone (the type is declared in the prelude; literal 2026-11-03T18:00).
enum `Missed`	What every does with ticks missed because the body was slow (§17.4).
data `Period`	Calendar interval (§17.1)
data `Schedule`	A cron expression bound to a zone (cron"0 9 MON-FRI".in(tz"Europe/Moscow")).
type `Time`	A UTC instant, nanoseconds since the Unix epoch (the type is declared in the prelude).
enum `TimeFormat`	Predefined text formats of parse (§17.5); every parse also accepts a pattern string instead.
data `TimeOfDay`	Wall-clock time of day, 00:00:00 ..
type `Tm`	type alias · std.time
type `Tz`	An IANA time zone (the type is declared in the prelude; literal tz"Europe/Moscow").
enum `Weekday`	Day of the week; Mon is the first.
data `ZonedTime`	An instant with a time zone (§17.1).

Functions

`after`	Runs body once after d (§17.4).
`at`	Runs body at every fire time of schedule until the task is cancelled (§17.4).
`every`	Runs body every d until the task is cancelled (§17.4).
`now`	Current UTC time (§17.3); same as the prelude now.
`sleep`	Suspends the current task (§17.4); same as the prelude sleep.
`today`	Today's date in tz (default

module std.time

Types

Functions

See also