package timezone

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Module type Timezone.Extend_zone

type t
include Core.Identifiable.S with type t := t
include Bin_prot.Binable.S with type t := t
include Bin_prot.Binable.S_only_functions with type t := t
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__ : (int -> t) Bin_prot.Read.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 with type t := t
include Sexplib0.Sexpable.S with type t := t
val t_of_sexp : Sexplib0.Sexp.t -> t
include Ppx_compare_lib.Comparable.S with type t := t
include Ppx_hash_lib.Hashable.S 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 Core.Comparable.S_binable with type t := t
include Base.Comparable.S 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

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
val between : t -> low:t -> high:t -> bool

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

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

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
type comparator_witness
val validate_lbound : min:t Core.Maybe_bound.t -> t Validate.check
val validate_ubound : max:t Core.Maybe_bound.t -> t Validate.check
val validate_bound : min:t Core.Maybe_bound.t -> max:t Core.Maybe_bound.t -> t Validate.check
module Replace_polymorphic_compare : Base.Comparable.Polymorphic_compare with type t := t
val comparator : (t, comparator_witness) Base__.Comparator.comparator
include Core.Hashable.S_binable with type t := t
include Ppx_hash_lib.Hashable.S with type t := t
val hash_fold_t : t Base__.Ppx_hash_lib.hash_fold
val hash : t -> Base__.Hash.hash_value
val hashable : t Core.Hashtbl.Hashable.t
module Table : Core.Hashtbl.S_binable with type key = t
module Hash_set : Core.Hash_set.S_binable with type elt = t
module Hash_queue : Core.Hash_queue.S with type key = t
val find : string -> t option

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
  • lon -> Europe/London
  • tyo -> Asia/Tokyo
val find_exn : string -> t
val local : t Core.Lazy.t

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 initialized_zones : unit -> (string * t) list

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 : unit -> unit

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.