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 <[email protected]> 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 <[email protected]> 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 <
>> [email protected]> 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 <[email protected]> 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!
>>> >
>>>
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