I agree that option (1) is more pragmatic. I still worry that `Date.day_of_week/2` returns ordinal numbers in all but one very specific (but almost ubiqtuious) case for Calendar.ISO. So documentating that the analogous case for all compliant calendar is a reasonable compromise.
Proposal closed. > On 11 Jan 2025, at 9:54 pm, José Valim <jose.va...@gmail.com> wrote: > > > My only intent was to define a standard Elixir API where, for any given > > date in any complying calendar, I could know upon which day of the week > > that day falls. > > So I can think of two options: > > 1. You can use the atom :monday, as that should return the same meaning on > all calendars based on our weekdays? In the same way that passing :sunday to > Calendar.ISO makes it return the same value as "Calendar.USA". The benefit of > this option is that it is supported for quite some time. > > 2. We introduce a new option, called :iso8601, which returns the default for > iso8601, which is therefore :monday. > > My preference is 1 but I am open to hearing it is a bad idea. :D > > > José Valim > https://dashbit.co/ > > > On Sat, Jan 11, 2025 at 11:37 AM Kip Cole <kipco...@gmail.com > <mailto:kipco...@gmail.com>> wrote: >> > Also, in your case, couldn't you support a custom starting_on value called >> > :iso_default or :monday, which will behave as you described? >> >> In everything I do I try very hard to have a consistent implementation of >> the Calendar behaviour. I believe that in most cases a user or developer >> shouldn’t have to think about what calendar is in use - it’s just the right >> calendar producing the right results. So while I could implement a custom >> `starting_on`, that then sets my calendars apart from the default calendar >> and other peoples calendars. I really really really want to avoid that. >> Calendaring is hard enough as it is without developers having to >> differentiate between them in their code. >> >> > my concern with this PR is that it opens up the path for "duplicating" >> > several of the functions in the Date module >> >> I’m just a pragmatist and a bit gun shy to argue any point here. My only >> intent was to define a standard Elixir API where, for any given date in any >> complying calendar, I could know upon which day of the week that day falls. >> >> If I’m the only person who thinks that’s a reasonable expectation then there >> is no need to consider the proposal further. >> >> >> >>> On 11 Jan 2025, at 8:33 pm, José Valim <jose.va...@gmail.com >>> <mailto:jose.va...@gmail.com>> wrote: >>> >>> Hi Kip, my concern with this PR is that it opens up the path for >>> "duplicating" several of the functions in the Date module: >>> >>> Date.iso_beginning_of_month/1 >>> Date.iso_beginning_of_week/2 >>> Date.iso_day_of_era/1 >>> Date.iso_day_of_week/1 >>> Date.iso_day_of_year/1 >>> Date.iso_days_in_month/1 >>> Date.iso_end_of_month/1 >>> Date.iso_end_of_week/2 >>> Date.iso_months_in_year/1 >>> Date.iso_quarter_of_year/1 >>> Date.iso_year_of_era/1 >>> >>> Perhaps not all of the above but at least a few. >>> >>> Also, in your case, couldn't you support a custom starting_on value called >>> :iso_default or :monday, which will behave as you described? >>> >>> So your :default can adhere to your custom calendar semantics, and then >>> either :monday or :iso_default returns what the computation above would >>> provide. >>> >>> >>> José Valim >>> https://dashbit.co/ >>> >>> >>> On Sat, Jan 11, 2025 at 9:45 AM Kip <kipco...@gmail.com >>> <mailto:kipco...@gmail.com>> wrote: >>>> A recent discussion <https://github.com/elixir-lang/elixir/pull/14162> >>>> clarified that the return value from `Date.day_of_week/2` is an ordinal >>>> value. That is, when it returns "1" that means "first day of week". It >>>> specifically does not mean "1" is Monday. >>>> >>>> That means that it would be useful to have a function that does return the >>>> cardinal day of week - that is, a number where 1 == Monday and 7 == Sunday. >>>> >>>> The function would look something like: >>>> >>>> def iso_day_of_week(%{calendar: Calendar.ISO} = date) do >>>> day_of_week(date) >>>> end >>>> >>>> def iso_day_of_week(date) do >>>> date >>>> |> convert!(Calendar.ISO) >>>> |> day_of_week() >>>> end >>>> >>>> This implementation relies on the knowledge that when called with >>>> starting_on = :default (which is the default argument value) the returned >>>> value is indeed 1 == Monday, 7 == Sunday. >>>> >>>> If there is any consensus I'll submit a PR. >>>> >>>> >>>> >>>> -- >>>> 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 >>>> <mailto:elixir-lang-core+unsubscr...@googlegroups.com>. >>>> To view this discussion visit >>>> https://groups.google.com/d/msgid/elixir-lang-core/eeff3e35-448b-4dcf-ad4a-866bac76a819n%40googlegroups.com >>>> >>>> <https://groups.google.com/d/msgid/elixir-lang-core/eeff3e35-448b-4dcf-ad4a-866bac76a819n%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 >>> <mailto:elixir-lang-core+unsubscr...@googlegroups.com>. >>> To view this discussion visit >>> https://groups.google.com/d/msgid/elixir-lang-core/CAGnRm4K1Avrg-Ro_%3DWdNTtwOM9CV-oWPPbn2rprG%2B5en9XPwOA%40mail.gmail.com >>> >>> <https://groups.google.com/d/msgid/elixir-lang-core/CAGnRm4K1Avrg-Ro_%3DWdNTtwOM9CV-oWPPbn2rprG%2B5en9XPwOA%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 >> <mailto:elixir-lang-core+unsubscr...@googlegroups.com>. >> To view this discussion visit >> https://groups.google.com/d/msgid/elixir-lang-core/B942BE1E-5FC3-4A0E-AE31-19267B436AD1%40gmail.com >> >> <https://groups.google.com/d/msgid/elixir-lang-core/B942BE1E-5FC3-4A0E-AE31-19267B436AD1%40gmail.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 > <mailto:elixir-lang-core+unsubscr...@googlegroups.com>. > To view this discussion visit > https://groups.google.com/d/msgid/elixir-lang-core/CAGnRm4KREP%3D75b6OuKqGheXTDXPke_hou6rdEfw-2bVxGa7fOg%40mail.gmail.com > > <https://groups.google.com/d/msgid/elixir-lang-core/CAGnRm4KREP%3D75b6OuKqGheXTDXPke_hou6rdEfw-2bVxGa7fOg%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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