Correct.
On Tuesday, August 20, 2019 at 9:53:42 PM UTC-6, Andrea Leopardi wrote:
>
> I’m slightly confused on why we would need to handle nested {:ok, {:ok,
> _}} tuples. Is that for async_stream specifically?
>
> On Tue, 20 Aug 2019 at 20:21, Spencer Carlson <[email protected]
> <javascript:>> wrote:
>
>> Given the
>>
>> {ok, result} | {:error, result}
>>
>> convention and the beautiful nature of piping, I often find myself
>> looking for an elegant way to "strain" out all of the {:error _} results in
>> the middle of a pipe so I can continue processing the results that were
>> successful. I know the Enum and Stream modules already have a lot of
>> functions but I think a strain function would add significant value
>> especially in overall code readability.
>>
>> Here is a possible source example
>>
>> def strain(enumerable) do
>> Enum.reduce(enumerable, [], fn
>> {:ok, tuple}, acc when is_tuple(tuple) ->
>> case tuple do
>> {:ok, result} -> [result | acc]
>> {:error, _} -> acc
>> end
>> {:ok, result}, acc -> [result | acc]
>> _, acc -> acc
>> end)
>> end
>>
>> And an overloaded version that allows for handling errors:
>>
>> def strain(enumerable, fun) do
>> Enum.reduce(enumerable, [], fn
>> {:ok, tuple}, acc when is_tuple(tuple) ->
>> case tuple do
>> {:ok, result} -> [result | acc]
>> {:error, result} ->
>> fun.(result)
>> acc
>> end
>> {:ok, result}, acc -> [result | acc]
>> {:error, result}, acc ->
>> fun.(result)
>> acc
>> _, acc -> acc
>> end)
>> end
>>
>>
>> This would allow client code to look like this:
>>
>> results = list
>> |> Enum.map(&do_something/1)
>> |> Enum.strain()
>> |> Task.async_stream(&do_another_expensive_thing/1)
>> |> Enum.strain()
>> |> Enum.to_list()
>>
>>
>> Simple examples (for clarity)
>> iex> Enum.strain([{:ok, "good job"}, {:error, "bad input"}])
>> ["good job"]
>>
>>
>> iex> Enum.strain([{:error, "bad input"}], &IO.inspect/1)
>> "bad input"
>> []
>>
>>
>> Thanks,
>> Spencer Carlson
>>
>>
>>
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>> <https://groups.google.com/d/msgid/elixir-lang-core/bff44726-95f0-4e71-8783-a67bfad043ef%40googlegroups.com?utm_medium=email&utm_source=footer>
>> .
>>
> --
>
> Andrea Leopardi
> [email protected] <javascript:>
>
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