[Proposal] Stream.map_reduce/3

[Michał Muskała]

I was looking recently into transforming a stream in a one-to-one way that requires maintaining an additional accumulator during the transition. That's an obvious use case for map_reduce with Enum, but with Stream we lack such a function. We have transform/3 that is somewhat equivalent to Enum.flat_map_reduce, that we could use here, but I think I'd prefer something simpler. I'm not 100% sure about the name, though.

Michał.

[José Valim]

Stream.transform is already optimized for cases where you emit one or zero element, so it is definitely the way to go. And we don't have any _reduce function in Stream exactly because you can't get the accumulator.

José Valim

www.plataformatec.com.br

Skype: jv.ptec

Founder and Director of R&D

On Fri, Jul 14, 2017 at 9:52 AM, Michał Muskała <mic...@muskala.eu> wrote:

I was looking recently into transforming a stream in a one-to-one way that requires maintaining an additional accumulator during the transition. That's an obvious use case for map_reduce with Enum, but with Stream we lack such a function. We have transform/3 that is somewhat equivalent to Enum.flat_map_reduce, that we could use here, but I think I'd prefer something simpler. I'm not 100% sure about the name, though.

Michał.

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[Michał Muskała]

Fair enough

Michał.

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