[swift-evolution] Reduce with inout

Xiaodi Wu xiaodi.wu at gmail.com
Tue Jan 17 17:30:55 CST 2017


Agree. The functional style should keep the functional name.
On Tue, Jan 17, 2017 at 16:18 David Sweeris via swift-evolution <
swift-evolution at swift.org> wrote:

>
> On Jan 17, 2017, at 16:11, Karl Wagner via swift-evolution <
> swift-evolution at swift.org> wrote:
>
>
> On 17 Jan 2017, at 23:09, Karl Wagner <karl.swift at springsup.com> wrote:
>
>
> On 16 Jan 2017, at 14:49, Chris Eidhof via swift-evolution <
> swift-evolution at swift.org> wrote:
>
> Hi,
>
> How does everyone feel about adding a second version of `reduce` to
> `Sequence`? Instead of a `combine` function that's of type `(A, Element) ->
> A`, it would be `(inout A, Element) -> ()`. This way, we can write nice
> functionals algorithms, but have the benefits of inout (mutation within the
> function, and hopefully some copy eliminations).
>
> IIRC, Loïc Lecrenier first asked this on Twitter. I've been using it ever
> since, because it can really improve readability (the possible performance
> gain is nice, too).
>
> Here's `reduce` with an `inout` parameter, including a sample:
> https://gist.github.com/chriseidhof/fd3e9aa621569752d1b04230f92969d7
>
> --
> Chris Eidhof
> _______________________________________________
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> swift-evolution at swift.org
> https://lists.swift.org/mailman/listinfo/swift-evolution
>
>
> +1
>
> I would even argue for it to be the default.
>
>
> I mean, assuming having two “reduce”s would stress the typechecker, as Joe
> suggested it might, I would say “inout” makes sense to be the default and
> the other one can find itself a new name.
>
>
> IIRC, the "reduce" name comes from functional programming... should the
> functional style keep the functional name?
>
> - Dave Sweeris
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> swift-evolution at swift.org
> https://lists.swift.org/mailman/listinfo/swift-evolution
>
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