> Here is another question: if we are going to parse ordinals by default, how am I going to format to the ordinal format? Use strftime exclusively?
I'm fine with that, to me this is a case of following the parsing spec and being liberal in what we accept, conservative in what we emit (by default). On Thursday, February 4, 2021 at 3:20:21 PM UTC-8 Christopher Keele wrote: > > Ordinal also has both extended and basic forms too. > > Yup, basic/extended can apply to the entire date/time/datetime string (but > must be universally applied to it, saving at least some headache). > > > The distinction between basic ordinal and basic DateTime is a single > character > > I agree that basic ordinals is possibly the worst way to format a date, > for the reasons you describe. But it is technically unambiguous, and > > > There will also be ambiguity if we ever decide to support more than four > digits on the year. > > This is technically not true for 5-digit years, so long as we choose to > use ISO-8601: it has a provision for this by prefixing the year with a plus > or minus. This is described as being 'by agreement only' though so omitted > from my envisioned scope. > > In fact now that I think about it we are probably violating the spec > today: we support negative signs to indicate BC for 4-digit years. By my > reading of the spec we should be requiring that negative years supply 5 > digits. > > > At this point I wonder why add [ordinal dates] to the stdlib. > > My motive here really is just to be spec-compliant. There may be a point > where we decide we are going off-spec to avoid many of the complexities > raised in this discussion, happy to have that conversation too (though > probably should be its own thread?) > On Thursday, February 4, 2021 at 3:08:00 PM UTC-8 José Valim wrote: > >> Ah, thanks Kip. Ordinal also has both extended and basic forms too. >> >> Here is another question: if we are going to parse ordinals by default, >> how am I going to format to the ordinal format? Use strftime exclusively? >> >> The other annoyance is while an extended ordinal is distinct enough from >> a regular extended DateTime, the distinction between basic ordinal and >> basic DateTime is a single character: “2020012134523”. There will also be >> ambiguity if we ever decide to support more than four digits on the year. >> This is enough to say that: >> >> * it is not possible to parse all formats within a single function >> without additional user instructions >> >> * if the basic format supports both regular and ordinal, there can be >> ambiguity if 5 year digits are ever supported in the future >> >> This is enough information to me that ordinal should be its own thing, >> with possibly basic_ordinal and extended_ordinal, but at this point I >> wonder why add it to the stdlib. >> >> On Thu, Feb 4, 2021 at 23:50 Kip Cole <[email protected]> wrote: >> >>> From ISO 8601-1:2019(E): >>> >>> 5.2.3 Ordinal date >>> >>> >>> 5.2.3.1 Complete representations >>> >>> A complete representation of an ordinal date shall be as follows. >>> >>> a) Basic format: [year][dayo] EXAMPLE 1 1985102 >>> >>> b) Extended format: [year][“-”][dayo] EXAMPLE 2 1985-102 >>> >>> If by agreement, expanded representations are used, the formats shall be >>> as specified below. The interchange parties shall agree on the additional >>> number of digits in the time scale component year. >>> >>> 5.2.3.2 Expanded representations >>> >>> In the examples below it has been agreed to expand the time scale >>> component year with two digits. >>> >>> a) Basic format: [±][year(6)][dayo] EXAMPLE 1 +001985102 >>> >>> b) Extended format: [±][year(6)][“-”][dayo] EXAMPLE 2 +001985-102 >>> >>> On 5 Feb 2021, at 6:45 am, José Valim <[email protected]> wrote: >>> >>> >>> >>>> I like José's suggesting of supporting a flag, but it gets kind of >>>> complicated as there are several dimensions here even in our reduced case. >>>> Dates, times, and datetimes support either basic or extended notations; >>>> dates and datetimes support calendar dates or ordinal dates; both are >>>> applicable to any parsing. >>>> >>> >>> Are we 100% sure that ordinal datetimes are part of ISO8601? Kip, can >>> you please confirm? >>> >>> >>>> If we went with this approach I'd lean towards always accepting either >>>> form for one of the dimensions, and using flags to the sigil and parsing >>>> functions to indicate intent for the other. >>>> >>> >>> I am not necessarily worried about sigils because sigils are always >>> compile-time literals. It is probably fine to enforce a given format there >>> rather than multiple ones. >>> >>> >>> -- >>> You received this message because you are subscribed to a topic in the >>> Google Groups "elixir-lang-core" group. >>> To unsubscribe from this topic, visit >>> https://groups.google.com/d/topic/elixir-lang-core/CcXpeMQhsmU/unsubscribe >>> . >>> To unsubscribe from this group and all its topics, send an email to >>> [email protected]. >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/elixir-lang-core/CAGnRm4JNeGkCNW_6ic2XkxTkFV3uyMT%2B3EZYJuguhzzZfpOnpQ%40mail.gmail.com >>> >>> <https://groups.google.com/d/msgid/elixir-lang-core/CAGnRm4JNeGkCNW_6ic2XkxTkFV3uyMT%2B3EZYJuguhzzZfpOnpQ%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 [email protected]. >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/elixir-lang-core/15198E56-9D02-4A0E-8E6D-AB905531112A%40gmail.com >>> >>> <https://groups.google.com/d/msgid/elixir-lang-core/15198E56-9D02-4A0E-8E6D-AB905531112A%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 [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/elixir-lang-core/d23cddf9-5f10-4618-b6c7-a0902b828bd2n%40googlegroups.com.
