After a quick glance on other programming languages, it seems Python, Java, Rust, and C# all have plural names. Erlang also uses plural in its helper functions in the timer module. So we might want to follow suit.
On Wed, Mar 6, 2024 at 23:03 José Valim <jose.va...@dashbit.co> wrote: > We discussed plural vs singular and settled on singular so it mirrors the > calendar types. Thoughts? > > On Wed, Mar 6, 2024 at 23:01 Panagiotis Nezis <pne...@gmail.com> wrote: > >> +1 for this, awesome work Theo. Shifting dates/timestamps is such a >> common operation and a standard implementation would be beneficial for >> everybody. >> >> PS. I would expect plural in the duration fields. >> >> On Wed, Mar 6, 2024 at 8:23 PM José Valim <jose.va...@dashbit.co> wrote: >> >>> The main argument for having it in core is: >>> >>> * It integrates directly with the Calendar behaviour >>> * We could provide built-in sigils in the future to create readable >>> durations, such as ~P[3 hours and 10 minutes] >>> * Postgrex, Explorer, CLDR, etc all implement their own version of >>> durations >>> >>> Arguments for not having it in core: it happens that all of the >>> arguments above can also be solved without adding Duration to Elixir and, >>> instead, by creating a custom library: >>> >>> * A separate library could extend the calendar behaviour with shift_* >>> functions >>> * Third-party sigils can also be provided by libraries >>> * Postgrex, Explorer, and CLDR could create or use a package with a >>> duratio type shared across them all >>> >>> I would love to hear the community thoughts. >>> >>> On Wed, Mar 6, 2024 at 7:16 PM 'Theo Fiedler' via elixir-lang-core < >>> elixir-lang-core@googlegroups.com> wrote: >>> >>>> *Preface* >>>> >>>> We currently have `add/2-3` to manipulate calendar types in the >>>> standard library. These functions allow adding a specified amount of time >>>> of given unit to a date/time. The standard library currently misses means >>>> to apply more complex, or logical *durations *to calendar types. e.g. >>>> adding a month, a week, or one month and 10 days to a date. >>>> >>>> *Reasons for it* >>>> >>>> While similar functionality exists in libraries, such as CLDR, >>>> Timex, Tox, adding this functionality to the standard library has already >>>> been requested and discussed at multiple occasions over the past years. To >>>> list a few examples: >>>> >>>> - https://github.com/elixir-lang/elixir/pull/10199 >>>> - https://elixirforum.com/t/get-date-n-months-years-in-the-past/48346/3 >>>> - >>>> https://elixir-lang.slack.com/archives/C0HEX82NR/p1709581478427009?thread_ts=1709368588.334759&cid=C0HEX82NR >>>> >>>> Furthermore the shift behaviour in the extremely popular library Timex >>>> changed <https://github.com/bitwalker/timex/issues/731> in Elixir >= >>>> 1.14.3 which may have complicated the mostly lean and non-breaking language >>>> upgrade Elixir has to offer. >>>> >>>> Elixir has a great set of modules and functions that deal with date and >>>> time, the APIs are consistent and `shift/2-3` should fit right in, solving >>>> many standard needs of various industries, be it for reporting, >>>> appointments, events, finance... the list goes on, engineers probably face >>>> the need to shift time logically more often than not in their careers. >>>> >>>> *Technical details* >>>> >>>> Duration >>>> A date or time must be shifted by a *duration*. There is an ISO8601 >>>> for durations <https://en.wikipedia.org/wiki/ISO_8601#Durations>, >>>> which the initial implementation is loosely following. The structure of a >>>> Duration lives in its own module with its own set of functions to create >>>> and manipulate durations. One example of where it diverts from the ISO >>>> standard, is that it implements microseconds. Microseconds in a >>>> *duration* are stored in the same format as in the time calendar >>>> types, meaning they integrate well and provide consistency. >>>> >>>> Shift >>>> The shift behaviour is implemented as a callback on Calendar and >>>> supported by all calendar types: Date, DateTime, NaiveDateTime and Time. >>>> Date, Time and NaiveDateTime each have their own implementation of a >>>> "shift", while DateTime gets converted to a NaiveDateTime before applying >>>> the shift, and is then rebuilt to a DateTime in its original timezone. >>>> `shift/2-3` also has guaranteed output types (which isn't a given in many >>>> libraries) and follows the consistent API which is established in the >>>> calendar modules. >>>> >>>> Find the current state of the implementation here: >>>> https://github.com/elixir-lang/elixir/pull/13385 >>>> >>>> *Benchmarks* >>>> >>>> There are some benchmarks + StreamData tests in the PR description. >>>> >>>> *Outlook* >>>> >>>> *After *adding the Duration type and shift behaviour to the standard >>>> library, the following things could be explored and derived from the >>>> initial work: >>>> >>>> >>>> - Implementing a protocol that allows Duration to be applied to any >>>> data type, not just dates and times. >>>> - A range-like data type that allows us to do recurring constructs >>>> on any data type. For example, Duration.interval(~D[2000-01-01], >>>> month: 1), when iterated, would emit {:ok, date} | {:error, start, >>>> duration, reason} entries >>>> - A sigil for easy creation of durations: ~P[3 hours and 10 minutes] >>>> - Making it so add/2-3 reuses the shift_* functions >>>> >>>> *Reasons against it* >>>> >>>> While I am convinced that adding `shift/2-3` to the standard library >>>> would be very beneficial, nothing really speaks against the points >>>> mentioned above to be implemented in a library instead. However, something >>>> as crucial and central as date/time manipulation should still be part of >>>> the standard library, negating the risk of breaking changes, inconsistent >>>> behaviour and outdated or too unique ergonomics which aren't widely >>>> applicable, unlike what should be part of the standard library. >>>> >>>> Many thanks to @jose & @kip for the initial reviews and everyone in >>>> advance taking the time to read the proposal! >>>> >>>> Looking forward to hear other peoples ideas and opinions on the subject! >>>> >>>> -- >>>> You received this message because you are subscribed to the Google >>>> Groups "elixir-lang-core" group. >>>> To unsubscribe from this group and stop receiving emails from it, send >>>> an email to elixir-lang-core+unsubscr...@googlegroups.com. >>>> To view this discussion on the web visit >>>> https://groups.google.com/d/msgid/elixir-lang-core/cb0ed628-3848-4de0-aa13-c0f4761e4d99n%40googlegroups.com >>>> <https://groups.google.com/d/msgid/elixir-lang-core/cb0ed628-3848-4de0-aa13-c0f4761e4d99n%40googlegroups.com?utm_medium=email&utm_source=footer> >>>> . >>> >>> >>>> -- >>> You received this message because you are subscribed to the Google >>> Groups "elixir-lang-core" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to elixir-lang-core+unsubscr...@googlegroups.com. >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/elixir-lang-core/CAGnRm4%2BNmFsMhbkRubMjnmM8c_Amq8DgmKCJtzJ1GEuM4-sVgw%40mail.gmail.com >>> <https://groups.google.com/d/msgid/elixir-lang-core/CAGnRm4%2BNmFsMhbkRubMjnmM8c_Amq8DgmKCJtzJ1GEuM4-sVgw%40mail.gmail.com?utm_medium=email&utm_source=footer> >>> . >>> >> -- >> You received this message because you are subscribed to the Google Groups >> "elixir-lang-core" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to elixir-lang-core+unsubscr...@googlegroups.com. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/elixir-lang-core/CAPxxbtjvFwnMXe134RR8wjnYk%2Bm-%2BF%2BO_79dWKk3G-bt99Ln%2Bw%40mail.gmail.com >> <https://groups.google.com/d/msgid/elixir-lang-core/CAPxxbtjvFwnMXe134RR8wjnYk%2Bm-%2BF%2BO_79dWKk3G-bt99Ln%2Bw%40mail.gmail.com?utm_medium=email&utm_source=footer> >> . >> > -- You received this message because you are subscribed to the Google Groups "elixir-lang-core" group. 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