[swift-evolution] Reduce with inout

[Chris Eidhof]

I don't think we should replace the current `reduce` with the `inout`
version, also because the current reduce can be really useful as well (e.g.
when the return type is an Int).

One downside of having a different name is that it'll be harder to discover
this version. If stressing the type-checker is the only problem, then maybe
we should improve the type-checker, instead of placing that burden on every
user of the language.



On Wed, Jan 18, 2017 at 9:36 AM, Karl Wagner via swift-evolution <
swift-evolution at swift.org> wrote:

>
> On 18 Jan 2017, at 09:00, Anton Zhilin via swift-evolution <
> swift-evolution at swift.org> wrote:
>
> While realizing that this name can cause confusion, I'd still prefer
> `reduce(mutating:_:)`, because it looks like the only readable option to me.
> Whatever name will be picked, I agree that traditional reduce without
> mutation should retain its name.
>
> 2017-01-18 5:17 GMT+03:00 Xiaodi Wu via swift-evolution <
> swift-evolution at swift.org>:
>
>> A serious possibility would be: `reduce(mutableCopyOf: x) { ... }`.
>>
>> It's verbose, but the nicer-looking `reduce(mutating: x) { ... }` is
>> incorrect since, as Charles pointed out to Dave, it's not `x` that's
>> mutated but rather a mutable copy of it, so it doesn't matter if `x` itself
>> is declared with `let` or `var`.
>>
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>
> I suppose as a second-choice I’d go for accumulate(into: with:):
>
> [1, 2, 3].accumulate(into: 0, with: +=)
>
> even [1, 2, 3].accumulate(into: 0, with: -=) doesn’t look so bad IMO.
>
> - Karl
>
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-- 
Chris Eidhof
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