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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