I really like this, and would be happy with it as is 😁 I have one thought
though, with the way that we are already doing a bit of “magic” (I don’t mean
that in a negative way) to map the “let” variable to the second element of the
tuple, could we support multiple assignments without the tuple in the let?
Something like this (hard to type code on the phone 😂)
for let x = 10, y = 12, foo <- list do
{result, x, y}
end
Sent via Superhuman iOS ( https://sprh.mn/?vip=zachary.s.dan...@gmail.com )
On Tue, Dec 21 2021 at 4:09 PM, Stefan Chrobot < ste...@chrobot.io > wrote:
>
> I'm too voting in favor of the proposal in the current form. Unsure about
> the parens, but looking forward to some way of replacing reduce_while with
> some version of the for.
>
>
> Best,
> Stefan
>
> wt., 21 gru 2021 o 21:47 Christopher Keele < christheke...@gmail.com >
> napisał(a):
>
>
>> *Guides Feedback*
>> *
>> *
>> These look excellent, should make the power of for much more accessible.
>> *
>> *
>> *let Feedback*
>>
>>
>> I like the functionality of this proposal much more!
>>
>>
>> I will say, I'm still not a fan of using new qualifiers. I'm not sure why
>> we need to introduce a new special form for this, since we can do whatever
>> we need to in the macro? What's wrong with:
>>
>>
>> > for count = 0, count < 5, x <- element do {x, count + 1} end
>>
>>
>> Perfectly matches traditional for loops, and pattern matching in function
>> arguments, with all the familiar errors/warning possibly emitted from
>> them, while keeping the bodies identically functionally-refactorable. No let
>> s needed.
>>
>> Re: for reduce , since for already has idiomatic keyword arguments to
>> further modify functionality, isn't :reduce is doing fine as is? We'd just
>> document how it interacts with for-bindings.
>>
>>
>> > Furthermore, the introduction of let and reduce qualifiers opens up the
>> option for new qualifiers in the future, such as for async that is built
>> on top of Task.async_stream/3.
>> >
>> > Async doesn't have its own arguments
>>
>> (
>> https://gist.github.com/josevalim/fe6b0bcc728539a5adf9b2821bd4a0f5#naming
>> )
>>
>>
>> Similarly, I'm unsure what's wrong with add an async: true keyword
>> argument. It's just behaviour configuration, not something we need to
>> bring to the forefront as a pattern match?
>>
>>
>> *Replies*
>> *
>> *
>> > I am against the notion of `for_let` and `for_reduce`. I see that as
>> using up more of the special forms "namespace".
>>
>>
>> Agreed, mirroring my misgivings about "for let" and "for reduce".
>> On Tuesday, December 21, 2021 at 11:58:19 AM UTC-5 gva...@gmail.com wrote:
>>
>>
>>
>>> I'm a vote in favor of the proposal. I think I have a slight preference
>>> for the parens. But it's very slight, and I'm not sure I wouldn't change
>>> my mind after using it for a while.
>>>
>>>
>>> I am against the notion of `for_let` and `for_reduce`. I see that as using
>>> up more of the special forms "namespace".
>>>
>>>
>>> I'm slightly disappointed that the old style `reduce:` option will be
>>> deprecated (because I have old code I'll have to update) however, the
>>> change does make things more consistent and I appreciate the thought about
>>> future extensions to for comprehensions.
>>>
>>>
>>> -Greg Vaughn
>>>
>>>
>>> PS. I just watched your latest Twitch stream. I wish I could have been
>>> there live to hear you read the dictionary and to offer obscure English
>>> words to the bikeshed discussion :-D
>>>
>>>
>>>>
>>>
>>>
>>>
>>>> On Dec 21, 2021, at 3:31 AM, José Valim < jose....@dashbit.co > wrote:
>>>>
>>>>
>>>
>>>
>>>
>>>> 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-l...@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-l...@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 < benwil...@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
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>>>>> > > >>>>>> To view this discussion on the web visit
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>>>>>
>>>>> > > >>>>>> .
>>>>> > > >>>>>>
>>>>> > > >>>>> --
>>>>> > > >>>>> You received this message because you are subscribed to the
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>>>>>
>>>>> > > >>>>> <
>>>>> > > >>>>> 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
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>>>>> > > >>>
>>>>> > > >> To view this discussion on the web visit
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>>>>>
>>>>> > > >>> <
>>>>> > > >>> https://groups.google.com/d/msgid/elixir-lang-core/CACzMe7aXBL1jNM_aWmJJzYOjrK%3Dtf-4%2BLPLJLpccu_G4zr0cAg%40mail.gmail.com?utm_medium=email&utm_source=footer
>>>>> >
>>>>> > > >>> .
>>>>> > > >>>
>>>>> > > >> --
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>>>>>
>>>>> > > > <
>>>>> > > > https://groups.google.com/d/msgid/elixir-lang-core/c1fea9e2-f47c-4236-812a-431bc7d76d62n%40googlegroups.com?utm_medium=email&utm_source=footer
>>>>> >
>>>>> > > > .
>>>>> > > >
>>>>> > >
>>>>> >
>>>>>
>>>>> --
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>>>>> .
>>>>>
>>>>
>>>>
>>>>
>>>>
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>>>
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>>>> (
>>>> https://groups.google.com/d/msgid/elixir-lang-core/CAGnRm4K9WRhyaGpXy8Ds%3DbEq%3DpapgF6w%2BRciB-PY6M6Xe5%2BoFQ%40mail.gmail.com?utm_medium=email&utm_source=footer
>>>> ).
>>>>
>>>>
>>>
>>>
>>>
>>>
>>
>>
>>
>>
>>
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