Any thoughts about adding the early-exit semantics? As for the parens, I was actually in favor of keeping them. "for let" and "for reduce" seem like different variants of "for", which raises the question if maybe they should be "for_let" and "for_reduce" instead.
Does this mean that the formatter will drop the parens? Best, Stefan wt., 21 gru 2021 o 10:31 José Valim <jose.va...@dashbit.co> napisał(a): > Compared to the previous proposal, this one has been very quiet so far. :) > I am unsure if it was because it was a Monday or because holidays are > coming, so I am sending a ping. > > ALso note I updated the proposal to not use parens around let/reduce, > which seems to be the preference so far: > https://gist.github.com/josevalim/fe6b0bcc728539a5adf9b2821bd4a0f5 > > On Tue, Dec 21, 2021 at 1:29 AM 'eksperimental' via elixir-lang-core < > elixir-lang-core@googlegroups.com> wrote: > >> Not necessarily that they are replaceable, >> but that pattern of :cont, :halt, :suspend is most commonly used via >> Enumerable.reduce >> >> >> On Mon, 20 Dec 2021 19:18:53 -0500 >> "'eksperimental' via elixir-lang-core" >> <elixir-lang-core@googlegroups.com> wrote: >> >> > > I have found only one usage of Enum.reduce_while in Elixir's >> > > codebase. >> > >> > This is because under the hood Enum.reduce_while is a call >> > `Enumerable.reduce/3`, so we are invoking this functions direcly. >> >> > >> > On Tue, 21 Dec 2021 00:47:44 +0100 >> > Stefan Chrobot <ste...@chrobot.io> wrote: >> > >> > > Thanks, that version would work, but agreed - not sure how big of an >> > > improvement that would be over Enum.reduce_while. Trying to think >> > > about this in a more imperative style, it seems that maybe an >> > > equivalent of break is what I'm after? Maybe something close to >> > > Ecto's Repo.transaction semantics? >> > > >> > > for foo <- foos do >> > > case barify(foo) do >> > > {:ok, bar} -> bar >> > > {:error, reason} -> break(reason) >> > > end >> > > end >> > > >> > > I think this would have to work similarly to how Ecto's transactions >> > > work with Multis, that is return {:ok, bars} or {:error, reason, >> > > data_so_far}. >> > > >> > > I have found only one usage of Enum.reduce_while in Elixir's >> > > codebase. Interestingly, the shape of the return value is always >> > > the same - a list of finished tests. >> > > >> https://github.com/elixir-lang/elixir/blob/main/lib/ex_unit/lib/ex_unit/runner.ex#L340 >> > > >> > > This seems like a separate problem, but maybe something to keep in >> > > mind. >> > > >> > > Best, >> > > Stefan >> > > >> > > >> > > wt., 21 gru 2021 o 00:21 Ben Wilson <benwilson...@gmail.com> >> > > napisał(a): >> > > >> > > > To revisit the example situation from the original post: >> > > > >> > > > ``` >> > > > {sections, _acc} = >> > > > for let {section_counter, lesson_counter} = {1, 1}, section <- >> > > > sections do lesson_counter = if section["reset_lesson_position"], >> > > > do: 1, else: lesson_counter >> > > > {lessons, lesson_counter} = for let lesson_counter, lesson <- >> > > > section["lessons"] do >> > > > {Map.put(lesson, "position", lesson_counter), lesson_counter + 1} >> > > > end >> > > > section = >> > > > section >> > > > |> Map.put("lessons", lessons) >> > > > |> Map.put("position", section_counter) >> > > > >> > > > {section, {section_counter + 1, lesson_counter}} >> > > > end >> > > > ``` >> > > > >> > > > I think that's nice! It focuses on inputs and outputs and reduces >> > > > the overall line noise. >> > > > >> > > > On Monday, December 20, 2021 at 5:28:29 PM UTC-5 José Valim wrote: >> > > > >> > > >> Stefan, this would work if we include all extensions: >> > > >> >> > > >> for reduce {status, acc} = {:ok, []}, status == :ok, foo <- foos >> > > >> do case barify(foo) do >> > > >> {:ok, bar} -> {:ok, [bar | acc]} >> > > >> >> > > >> {:error, _reason} = error -> error >> > > >> end >> > > >> end >> > > >> >> > > >> I am not sure if you find it any better. It is hard to do this >> > > >> with "let" because you don't want to include the element of when >> > > >> it fails. >> > > >> >> > > >> On Mon, Dec 20, 2021 at 9:23 PM Stefan Chrobot >> > > >> <ste...@chrobot.io> wrote: >> > > >>> I went through some of our code and one thing I'd love to see is >> > > >>> a way to replace Enum.reduce_while with the for comprehension. >> > > >>> So the code like this: >> > > >>> >> > > >>> Enum.reduce_while(foos, {:ok, []}, fn foo, {:ok, bars} -> >> > > >>> case barify(foo) do >> > > >>> {:ok, bar} -> {:cont, {:ok, [bar | bars]}} >> > > >>> {:error, _reason} = error -> {:halt, error} >> > > >>> end >> > > >>> end) >> > > >>> >> > > >>> Would the following even work? >> > > >>> >> > > >>> for reduce(result = {:ok, []}), foo <- foos, {:ok, _} <- result >> > > >>> do case barify(foo) do >> > > >>> {:ok, bar} -> {{:ok, [bar | bars]}} >> > > >>> {:error, _reason} = error -> {error} >> > > >>> end >> > > >>> end >> > > >>> >> > > >>> Even if it did, it's not doing a great job of communicating the >> > > >>> intent and still potentially requires a Enum.reverse call. The >> > > >>> intent here is "early exit with some value upon some condition >> > > >>> or pattern mismatch". >> > > >>> >> > > >>> >> > > >>> Best, >> > > >>> Stefan >> > > >>> >> > > >>> pon., 20 gru 2021 o 21:06 Stefan Chrobot <ste...@chrobot.io> >> > > >>> napisał(a): >> > > >>>> I really like this proposal! For me it strikes the perfect >> > > >>>> balance between terseness and explicitness that I've come to >> > > >>>> enjoy in Elixir. >> > > >>>> >> > > >>>> My votes: >> > > >>>> - Naming: let over given; just because it's shorter, >> > > >>>> - Do use parents: let "feels" similar to var!. >> > > >>>> >> > > >>>> Best, >> > > >>>> Stefan >> > > >>>> >> > > >>>> pon., 20 gru 2021 o 19:54 José Valim <jose....@dashbit.co> >> > > >>>> napisał(a): >> > > >>>>> Good point. I forgot to mention the :reduce option will be >> > > >>>>> deprecated in the long term. >> > > >>>>> >> > > >>>>> On Mon, Dec 20, 2021 at 7:53 PM 'eksperimental' via >> > > >>>>> elixir-lang-core < elixir-l...@googlegroups.com> wrote: >> > > >>>>> >> > > >>>>>> The proposal is very concise, >> > > >>>>>> the only thing that would be problematic is the use of >> > > >>>>>> `reduce` for two >> > > >>>>>> different things, >> > > >>>>>> >> > > >>>>>> for <<x <- "AbCabCABc">>, x in ?a..?z, reduce: %{} do >> > > >>>>>> acc -> Map.update(acc, <<x>>, 1, & &1 + 1) >> > > >>>>>> end >> > > >>>>>> >> > > >>>>>> {sum, count} = >> > > >>>>>> for reduce({sum, count} = {0, 0}), i <- [1, 2, 3] do >> > > >>>>>> sum = sum + i >> > > >>>>>> count = count + 1 >> > > >>>>>> {sum, count} >> > > >>>>>> end >> > > >>>>>> >> > > >>>>>> It would lead to misunderstanding as it may not be clear >> > > >>>>>> which one we are talking about when we say "use for reduce" >> > > >>>>>> >> > > >>>>>> >> > > >>>>>> On Mon, 20 Dec 2021 19:11:54 +0100 >> > > >>>>>> José Valim <jose....@dashbit.co> wrote: >> > > >>>>>> >> > > >>>>>> > Hi everyone, >> > > >>>>>> > >> > > >>>>>> > This is the second proposal for-let. You can find it in a >> > > >>>>>> > gist: >> > > >>>>>> > >> https://gist.github.com/josevalim/fe6b0bcc728539a5adf9b2821bd4a0f5 >> > > >>>>>> > >> > > >>>>>> > Please use the mailing list for comments and further >> > > >>>>>> > discussion. Thanks for all the feedback so far! >> > > >>>>>> > >> > > >>>>>> >> > > >>>>>> -- >> > > >>>>>> 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-co...@googlegroups.com. >> > > >>>>>> To view this discussion on the web visit >> > > >>>>>> >> https://groups.google.com/d/msgid/elixir-lang-core/61c0d119.1c69fb81.af520.c181SMTPIN_ADDED_MISSING%40gmr-mx.google.com >> > > >>>>>> . >> > > >>>>>> >> > > >>>>> -- >> > > >>>>> 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-co...@googlegroups.com. >> > > >>>>> To view this discussion on the web visit >> > > >>>>> >> https://groups.google.com/d/msgid/elixir-lang-core/CAGnRm4LOyoAmXULJQo%2BYX4eFVJZJAoYtKHytoHujCS_kJ6AEuA%40mail.gmail.com >> > > >>>>> < >> https://groups.google.com/d/msgid/elixir-lang-core/CAGnRm4LOyoAmXULJQo%2BYX4eFVJZJAoYtKHytoHujCS_kJ6AEuA%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-co...@googlegroups.com. >> > > >>> >> > > >> To view this discussion on the web visit >> > > >>> >> https://groups.google.com/d/msgid/elixir-lang-core/CACzMe7aXBL1jNM_aWmJJzYOjrK%3Dtf-4%2BLPLJLpccu_G4zr0cAg%40mail.gmail.com >> > > >>> < >> https://groups.google.com/d/msgid/elixir-lang-core/CACzMe7aXBL1jNM_aWmJJzYOjrK%3Dtf-4%2BLPLJLpccu_G4zr0cAg%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/c1fea9e2-f47c-4236-812a-431bc7d76d62n%40googlegroups.com >> > > > < >> https://groups.google.com/d/msgid/elixir-lang-core/c1fea9e2-f47c-4236-812a-431bc7d76d62n%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/61c11ffb.1c69fb81.9b607.f827SMTPIN_ADDED_MISSING%40gmr-mx.google.com >> . >> > -- > 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/CAGnRm4K9WRhyaGpXy8Ds%3DbEq%3DpapgF6w%2BRciB-PY6M6Xe5%2BoFQ%40mail.gmail.com > <https://groups.google.com/d/msgid/elixir-lang-core/CAGnRm4K9WRhyaGpXy8Ds%3DbEq%3DpapgF6w%2BRciB-PY6M6Xe5%2BoFQ%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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