Module Time_float.Zone

User-friendly interface

type t

The type of a time-zone.

bin_io and sexp representations of Zone.t are the name of the zone, and not the full data that is read from disk when Zone.find is called. The full Zone.t is reconstructed on the receiving/reading side by reloading the zone file from disk. Any zone name that is accepted by find is acceptable in the bin_io and sexp representations.

val sexp_of_t__stack : t @ local -> Sexplib0.Sexp.t @ local
include Ppx_compare_lib.Comparable.S with type t := t
include Ppx_compare_lib.Comparable.S__local with type t := t
val input_tz_file : zonename:Base.String.t -> filename:Base.String.t -> t

input_tz_file ~zonename ~filename read in filename and return t with name t = zonename

val likely_machine_zones : Base.String.t Base.List.t Atomic.t

likely_machine_zones is a list of zone names that will be searched first when trying to determine the machine zone of a box. Setting this to a likely set of zones for your application will speed the very first use of the local timezone.

module Earlier_or_later : sig ... end

When there is a backwards DST transition, some local times can occur twice. Some functions that operate on local times accept an optional Earlier_or_later.t, which allows the user to explicitly specify whether the earlier or later of the two absolute times corresponding to an ambiguous local time is intended.

val of_utc_offset : hours:Base.Int.t -> t

of_utc_offset offset returns a timezone with a static UTC offset (given in hours).

val of_utc_offset_explicit_name : name:Base.String.t -> hours:Base.Int.t -> t

Like of_utc_offset, but overriding the default name. These zones can only be reliably transferred over sexp or bin-io using Stable.Full_data; see below.

val of_utc_offset_in_seconds_round_down : ?name:Base.String.t -> Time.Span.t -> t

Returns a timezone with a static UTC offset in units of seconds. Rounds input to the next lower unit of seconds if necessary. These zones can only be reliably transferred over sexp or bin-io using Stable.Full_data; see below.

val add_offset_in_seconds_round_down : t -> name:Base.String.t -> span:Time.Span.t -> t

Returns a timezone with a fixed offset relative to the given t in units of seconds. This time zone doesn't represent any real place, but may be convenient for testing or for other non-real-time purposes. Rounds span to the next lower unit of seconds if necessary. These zones can only be reliably transferred over sexp or bin-io using Stable.Full_data; see below.

val utc : t

utc the UTC time zone. Included for convenience

val name : t -> Base.String.t
val original_filename : t -> Base.String.t Base.Option.t

original_filename t return the filename t was loaded from (if any)

val digest : t -> Md5.t Base.Option.t

digest t return the MD5 digest of the file the t was created from (if any)

val reset_transition_cache : t -> Base.Unit.t

For performance testing only; reset_transition_cache t resets an internal cache in t used to speed up repeated lookups of the same clock shift transition.

module Index : sig ... end

A time zone index refers to a range of times delimited by DST transitions at one or both ends. Every time belongs to exactly one such range. The times of DST transitions themselves belong to the range for which they are the lower bound.

val index : t -> Time.t -> Index.t

Gets the index of a time.

val index_of_date_and_ofday : ?prefer:Earlier_or_later.t -> t -> Time.Date_and_ofday.t -> Index.t

Gets the index of an date and time of day in this zone. When there are two occurrences, the result is determined by prefer.

val index_offset_from_utc_exn : t -> Index.t -> Time.Span.t

Gets the UTC offset of times in a specific range.

This can raise if you use an Index.t that is out of bounds for this t.

val index_abbreviation_exn : t -> Index.t -> Base.String.t

index_abbreviation_exn t index returns the abbreviation name (such as EDT, EST, JST) of given zone t for the range of index. This string conversion is one-way only, and cannot reliably be turned back into a t. This function reads and writes the zone's cached index. Raises if index is out of bounds for t.

val index_has_prev_clock_shift : t -> Index.t -> Base.Bool.t

Accessors for the DST transitions delimiting the start and end of a range, if any. The _exn accessors raise if there is no such transition. These accessors are split up to increase performance and improve allocation; they are intended as a low-level back-end for commonly-used time conversion functions. See Time.Zone and Time_ns.Zone for higher-level accessors that return an optional tuple for clock shifts in either direction.

val index_prev_clock_shift_time_exn : t -> Index.t -> Time.t
val index_prev_clock_shift_amount_exn : t -> Index.t -> Time.Span.t
val index_has_next_clock_shift : t -> Index.t -> Base.Bool.t
val index_next_clock_shift_time_exn : t -> Index.t -> Time.t
val index_next_clock_shift_amount_exn : t -> Index.t -> Time.Span.t
val abbreviation : t -> Time.t -> Base.String.t

abbreviation t time returns the abbreviation name (such as EDT, EST, JST) of given zone t at time. This string conversion is one-way only, and cannot reliably be turned back into a t. This function reads and writes the zone's cached index.

val absolute_time_of_date_and_ofday : ?prefer:Earlier_or_later.t -> t -> Time.Date_and_ofday.t -> Time.t

absolute_time_of_date_and_ofday and date_and_ofday_of_absolute_time convert between absolute times and date + ofday forms. These are low level functions not intended for most clients. These functions read and write the zone's cached index.

When there are two absolute times at which a date/ofday occurs, the result is determined by prefer.

val date_and_ofday_of_absolute_time : t -> Time.t -> Time.Date_and_ofday.t
val next_clock_shift : t -> strictly_after:Time.t -> (Time.t * Time.Span.t) Base.Option.t

Takes a Time.t and returns the next Time.t strictly after it, if any, that the time zone UTC offset changes, and by how much it does so.

val next_clock_shift_incl : t -> at_or_after:Time.t -> (Time.t * Time.Span.t) Base.Option.t

As next_clock_shift, but *at or after* the given time.

val prev_clock_shift : t -> at_or_before:Time.t -> (Time.t * Time.Span.t) Base.Option.t

As next_clock_shift, but *at or before* the given time.

include Timezone.Extend_zone with type t := t
val t_sexp_grammar : t Sexplib0.Sexp_grammar.t @@ portable
include Identifiable.S__local__portable with type t := t
include Bin_prot.Binable.S__local with type t := t
include Bin_prot.Binable.S_only_functions__local with type t := t
include sig ... end
val bin_size_t : t Bin_prot.Size.sizer
val bin_write_t : t Bin_prot.Write.writer
val bin_read_t : t Bin_prot.Read.reader
val __bin_read_t__ : t Bin_prot.Read.vtag_reader

This function only needs implementation if t exposed to be a polymorphic variant. Despite what the type reads, this does *not* produce a function after reading; instead it takes the constructor tag (int) before reading and reads the rest of the variant t afterwards.

val bin_shape_t : Bin_prot.Shape.t
val bin_writer_t : t Bin_prot.Type_class.writer
val bin_reader_t : t Bin_prot.Type_class.reader
include Ppx_hash_lib.Hashable.S_any with type t := t
include Sexplib0.Sexpable.S with type t := t
include Sexplib0.Sexpable.Of_sexp with type t := t
val t_of_sexp : Sexplib0.Sexp.t -> t
include Sexplib0.Sexpable.Sexp_of with type t := t
include Ppx_compare_lib.Comparable.S with type t := t
include Ppx_compare_lib.Comparable.S__local with type t := t
include Ppx_hash_lib.Hashable.S_any with type t := t
val sexp_of_t : t -> Sexplib0.Sexp.t
include Base.Stringable.S with type t := t
val of_string : string -> t
val to_string : t -> string
include Base.Pretty_printer.S with type t := t
val pp : Base.Formatter.t -> t -> unit
include Base.Comparable.S__local__portable with type t := t
include Base.Comparisons.S__local with type t := t
include Base.Comparisons.Infix with type t := t
val (>=) : t -> t -> bool
val (<=) : t -> t -> bool
val (=) : t -> t -> bool
val (>) : t -> t -> bool
val (<) : t -> t -> bool
val (<>) : t -> t -> bool
val equal : t -> t -> bool
val compare : t -> t -> int

compare t1 t2 returns 0 if t1 is equal to t2, a negative integer if t1 is less than t2, and a positive integer if t1 is greater than t2.

val min : t -> t -> t
val max : t -> t -> t
val ascending : t -> t -> int @@ portable

ascending is identical to compare. descending x y = ascending y x. These are intended to be mnemonic when used like List.sort ~compare:ascending and List.sort ~cmp:descending, since they cause the list to be sorted in ascending or descending order, respectively.

val descending : t -> t -> int @@ portable
val between : t -> low:t -> high:t -> bool @@ portable

between t ~low ~high means low <= t <= high

val clamp_exn : t -> min:t -> max:t -> t @@ portable

clamp_exn t ~min ~max returns t', the closest value to t such that between t' ~low:min ~high:max is true.

Raises if not (min <= max).

val clamp : t -> min:t -> max:t -> t Base.Or_error.t @@ portable
include Base.Comparator.S__portable with type t := t
type comparator_witness
val validate_lbound : min:t Maybe_bound.t -> t Validate.check
val validate_ubound : max:t Maybe_bound.t -> t Validate.check
val validate_bound : min:t Maybe_bound.t -> max:t Maybe_bound.t -> t Validate.check
include Comparator.S__portable with type t := t with type comparator_witness := comparator_witness
include Hashable.S_binable with type t := t
include Ppx_hash_lib.Hashable.S_any with type t := t
val hash_fold_t : t Ppx_hash_lib.hash_fold
val hashable : t Base.Hashable.t
module Table : Hashtbl.S_binable with type key = t
module Hash_set : Hash_set.S_binable with type elt = t
module Hash_queue : Hash_queue.S with type key = t
include Diffable.S_atomic with type t := t
module Diff : sig ... end
val find : Base.String.t -> t Base.Option.t @@ portable

find name looks up a t by its name and returns it. This also accepts some aliases, including:

  • chi -> America/Chicago
  • nyc -> America/New_York
  • hkg -> Asia/Hong_Kong
  • ldn -> Europe/London
  • lon -> Europe/London
  • tyo -> Asia/Tokyo
  • syd -> Australia/Sydney
val find_exn : Base.String.t -> t @@ portable
val local : t Lazy.t @@ portable

local is the machine's local timezone, as determined from the TZ environment variable or the /etc/localtime file. It is computed from the state of the process environment and on-disk tzdata database at some unspecified moment prior to its first use, so its value may be unpredictable if that state changes during program operation. Arguably, changing the timezone of a running program is a problematic operation anyway -- most people write code assuming the clock doesn't suddenly jump several hours without warning.

Note that any function using this timezone can throw an exception if the TZ environment variable is misconfigured or if the appropriate timezone files can't be found because of the way the box is configured. We don't sprinkle _exn all over all the names in this module because such misconfiguration is quite rare.

val local_portable : t Portable_lazy.t @@ portable

Like local, but a Portable_lazy.t.

val initialized_zones : Base.Unit.t -> (Base.String.t * t) Base.List.t @@ portable

initialized_zones () returns a sorted list of time zone names that have been loaded from disk thus far.

Low-level functions

The functions below are lower level and should be used more rarely.

val init : Base.Unit.t -> Base.Unit.t @@ portable

init () pre-load all available time zones from disk, this function has no effect if it is called multiple times. Time zones will otherwise be loaded at need from the disk on the first call to find/find_exn.

val arg_type : t Command.Arg_type.t