OCaml date time handling and reasoning suite
This repo houses:
Timedesc - date time handling library
Timere - date time reasoning library
Timere-parse - date time and duration natural language parsing library
Note: The NLP component is WIP.
Disclaimer: Timere is not designed to handle prehistoric events. For prehistoric planning and booking software, please consult appropriate experts.
Christmases which fall on Wednesday from now
let () = let open Timere in match resolve ( since (Timedesc.now ()) &&& months  &&& days  &&& weekdays [`Wed] ) with | Error msg -> failwith msg | Ok s -> Fmt.pr "%a@." (Timedesc.Interval.pp_seq ~sep:(Fmt.any "@.") ()) s
[2024 Dec 25 00:00:00 +00:00:00, 2024 Dec 26 00:00:00 +00:00:00) [2030 Dec 25 00:00:00 +00:00:00, 2030 Dec 26 00:00:00 +00:00:00) [2041 Dec 25 00:00:00 +00:00:00, 2041 Dec 26 00:00:00 +00:00:00) [2047 Dec 25 00:00:00 +00:00:00, 2047 Dec 26 00:00:00 +00:00:00) [2052 Dec 25 00:00:00 +00:00:00, 2052 Dec 26 00:00:00 +00:00:00) [2058 Dec 25 00:00:00 +00:00:00, 2058 Dec 26 00:00:00 +00:00:00) ...
examples/ for more examples
Timestamp and date time handling with platform independent time zone support
Subset of the IANA time zone database is built into this library
Supports Gregorian calendar date, ISO week date, and ISO ordinal date
Supports nanosecond precision
ISO8601 parsing and RFC3339 printing
Reasoning over time intervals via
Pattern matching time and intervals. These work across DST boundaries.
Intersection and union
Chunking at year or month boundary, or in fixed sizes
Evaluate (sub)expressions with a different time zone (e.g. intersection of 9am to 5pm of Sydney and 9am to 5pm of New York)
timere-parse if needed) in the
libraries stanza in your dune file
You can optionally pick one of the following two concrete implementations of time zone data source
This is the default implementation which embeds the IANA time zone database from year 1850 to year 2100 exclusive
This embeds no database.
This is suitable for when you want to retrieve time zone data during run time, for instance, to reduce the built artifact size.
The following resources should allow you to implement said approach readily
A usable and test suite covered data source is provided under
List of available time zones is available as
Time_zone.JSON.of_stringcan load files in
You can optionally pick one of the following three concrete implementations of local time zone detection
This is the default implementation which tries to look up info of OS for local time zone name. Should work for common Linux distros.
This simply returns no time zone guesses
This simply returns UTC as the only guess
This is an implementation for
Intl.DateTimeFormatto get the local time zone name. Should work in all modern browsers, as well as node.js.
tzdb-json/ may be useful and usable outside of Timere,
we make no guarantees that the JSON format stays unmodified
(though changes of the format should be a rare occurrence, if ever occurring)
Using Timedesc in utop
To use Timedesc in utop, you need to pick the backends explicitly first
For example, to use the default implementations, one can first type the following lines in utop
#require "timedesc-tzdb.full";; #require "timedesc-tzlocal.unix";; #require "timedesc";;
Timedesc should be accessible in utop
Building a custom Tzdb backend
Timedesc itself can help build a time zone data source backend
Code files are licensed under the MIT license as specified in the
Time zone database derived files are licensed under its original terms (public domain)
Time zone information is extracted via
zdumpcommand output into
gen-artifacts/time_zone_db.sexp, using the IANA database (as time zone files) distributed on Linux
Time zone data handling code copies approach used by chrono-tz
This includes data representation and choices of some algorithms
Local time zone detection approach for
timedesc.tzlocal.unixbackend is copied from tzlocal
Some internal calculations/formulas in Timedesc based around Julian day are copied from Ptime