[swift-evolution] [Review] SE-0065 A New Model for Collections and Indices

[Xiaodi Wu]

On Mon, Apr 25, 2016 at 6:15 PM, Dave Abrahams <dabrahams at apple.com> wrote:

>
> on Mon Apr 25 2016, Xiaodi Wu <xiaodi.wu-AT-gmail.com> wrote:
>
> > Quick thought:
> >
> > Why are you reaching for the "form..." rule for the mutating methods
> when there
> > are clear verb counterparts?
> > location: locate
> > successor: succeed
>
> We're not using successor(i) anymore, as noted below, and furthermore
> c.succeed(&i) strongly implies the wrong meaning.


I thought that's what I understood from the email, but in the linked
proposal they're still there (as are the many types of Range protocols).
Wrong link, or just not updated?


> I didn't consider
> using
>
>   c. locate(...:&i ... )
>
> primarily because I never thought of it and nobody suggested it IIRC,
> but I also don't see how it would work in a family with
> c.location(after: i) et al.  Suggestions?
>

I didn't read this proposal carefully on its initial presentation for
review. Looking at it now, I wonder about the wisdom of "location"--I
understand the rationale of avoiding multiple methods named "index" that do
different things, but these particular functions return or mutate indices,
and nowhere else are these called "locations". If you're asking for
possible alternative suggestions to avoid using "index", I'll suggest the
following here because I don't recall seeing them offered previously. They
read as phrases or sentences:

```
// taking inspiration from ForwardIndexType, which is no more...
c.advancing(_ i: Index, by offset: IndexDistance, limit: Index)
c.advance(_ i: inout Index, by offset: IndexDistance, limit: Index)

// or alternatively, using the terminology in the comments that sit above
`location`
c.offsetting(_ i: Index, by n: IndexDistance, limit: Index)
c.offset(_ i: inout Index, by n: IndexDistance, limit: Index)

// and then, in place of successor, etc.
c.incrementing(_ i: Index, limit: Index)
c.increment(_ i: inout Index, limit: Index)
c.decrementing(_ i: Index, limit: Index)
c.decrement(_ i: inout Index, limit: Index)
```
("'Limit' doesn't read like a phrase," you might say. Well, think of a
coupon: "$1 off one tub of margarine. Limit one per purchase. Void if
transferred or sold.")


>
> > On Mon, Apr 25, 2016 at 1:24 PM, Dave Abrahams via swift-evolution
> > <swift-evolution at swift.org> wrote:
> >
> >     on Wed Apr 20 2016, Chris Lattner <swift-evolution at swift.org> wrote:
> >
> >     > On Apr 10, 2016, at 2:41 PM, Chris Lattner
> >     > <clattner at apple.com> wrote:
> >     >
> >     > Hello Swift community,
> >     >
> >     > The review of "A New Model for Collections and Indices" begins now
> and
> >     runs
> >     > through April 18th. The proposal is available here:
> >     >
> >     >
> >
> https://github.com/apple/swift-evolution/blob/master/proposals/0065-collections-move-indices.md
> >
> >     >
> >     > Reviews are an important part of the Swift evolution process. All
> reviews
> >     > should be sent to the swift-evolution mailing list at:
> >     > https://lists.swift.org/mailman/listinfo/swift-evolution
> >     > or, if you would like to keep your feedback private, directly to
> the
> >     review
> >     > manager.
> >     >
> >     > A quick update: the core team met to discuss this. They agreed to
> accept
> >     it with
> >     > some naming-related revisions to the proposal (in response to
> community
> >     > feedback). Dave is organizing this feedback, and I’ll send out the
> formal
> >     > announcement when that is ready.
> >
> >     The final revisions are reflected in the latest version of the
> >     proposal:
> >
> >
> https://github.com/apple/swift-evolution/blob/master/proposals/0065-collections-move-indices.md
> >
> >     Summary:
> >
> >     * We decided to take Shawn Erickson's excellent suggestion
> >     <http://article.gmane.org/gmane.comp.lang.swift.evolution/14450> to
> >     use “location” uniformly for index movement, so instead of
> >     successor(i) and predecessor(i) we have location(after: i) and
> >     location(before: i).
> >
> >     * Since Brent Royal-Gordon pointed out
> >     <
> http://news.gmane.org/find-root.php?message_id=156D8FB1%2d1FD3%2d448E%2d8C70%2d6E7400629BC0%40architechies.com
> >    >
> >     that two of the three proposed Range protocols would likely disappear
> >     in future updates, we took another look at all of them. Finding
> >     `RangeProtocol` itself to be a very weak abstraction, we removed all
> >     three from the proposal.
> >
> >     For those interested in details, implementation work proceeds apace
> on
> >     the swift-3-indexing-model branch at
> >     <
> https://github.com/apple/swift/tree/swift-3-indexing-model/stdlib/public/core
> >    >.
> >
> >     P.S. If anyone is interested in contributing, there are still plenty
> of
> >     FIXMEs left for us to handle ;-)
> >
> >     --
> >     Dave
> >
> >     _______________________________________________
> >     swift-evolution mailing list
> >     swift-evolution at swift.org
> >     https://lists.swift.org/mailman/listinfo/swift-evolution
> >
>
> --
> Dave
>
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