To clarify, the Ordered protocol would be like this: defprotocol Ordered do def ordered(data) end
Basically, it would work like Date.sortable, but implemented with a protocol so it works across data-types. *José Valimwww.plataformatec.com.br <http://www.plataformatec.com.br/>Founder and Director of R&D* On Thu, Oct 17, 2019 at 10:34 PM José Valim <jose.va...@gmail.com> wrote: > I have put more thoughts into this. > > If our goal is to have something that can be easily sortable, computed a > max and a min, etc, then the best option is to introduce a sortable > function: > > sortable(date) :: term() > > The goal of this function is to return a sortable term, according to > Erlang Term Ordering. > > Then we can do: > > Enum.sort_by(datetimes, &Date.sortable/1) > Enum.min_by(datetimes, &Date.sortable/1) > Enum.max_by(datetimes, &Date.sortable/1) > > If you want to sort users by their update date: > > Enum.sort_by(users, & &1.updated_at |> Date.sortable()) > Enum.min_by(users, & &1.updated_at |> Date.sortable()) > Enum.max_by(users, & &1.updated_at |> Date.sortable()) > > The only downside of this implementation is that it may not be as > efficient because we will have to convert to iso days so they are sortable > across calendars. > > === > > There is a longer discussion here about introducing a new protocol, called > Ordered, and an Enum.order/1 function. Then Enum.order(dates) would > automatically work, because it would dispatch to a protocol which is always > correct. This is all good on paper but I can foresee two downsides: > > 1. We would need to introduce an "Ordered" version of min/max. Perhaps > something like order_first/order_last or order_min/order_max. > > 2. I am not aware of any prior art on this. Most of the > protocols/typeclasses/interfaces I know for ordering build them based on > comparisons. Is anyone aware of a reference on the topic? > > Thoughts? > > -- > 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/56a992a6-0ae1-4d67-9145-dbee40935bae%40googlegroups.com > <https://groups.google.com/d/msgid/elixir-lang-core/56a992a6-0ae1-4d67-9145-dbee40935bae%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/CAGnRm4LpCxDOuUpg-HemPx-KPsjdUT5pkgoh-QJY6Rn3t4tDoQ%40mail.gmail.com.
