[swift-evolution] [swift-evolution-announce] [Review] SE-0187: Introduce Sequence.filterMap(_:)

[Howard Lovatt]

The review of "SE-0187: Introduce Sequence.filterMap(_:)" begins now and
runs through November 14th, 2017.  The proposal is available here:

https://github.com/apple/swift-evolution/blob/master/
proposals/0187-introduce-filtermap.md


• What is your evaluation of the proposal?
Worthwhile since there is a potential problem. However I am not convinced:

  1. About the name, it sounds like it filters and then maps rather than
what it really does which is map and then filter. Also, what does it
filter? How about mapFilterOptional (which is similar to Haskel name where
Maybe is equivalent of Optional).

  2. There is a more general problem of automatically wrapping a
non-optional in an optional; which this is a symptom off. So rather than
fix up the symptom, why not fix the problem. In particular; why not stop
the automatic conversion of a value to an optional, instead provide a value
to optional operator (the reverse of !). Say a trailing ~, used like 5~ to
mean Optional.some(5). ~ chosen because it is like an S, for some, on it's
side.

• Is the problem being addressed significant enough to warrant a change to
Swift?
Marginal

• Does this proposal fit well with the feel and direction of Swift?
Yes and no - see comments above. In particular automatic conversions are
not common in Swift. The conversion of a value to an optional automatically
therefore stands out.

• If you have used other languages or libraries with a similar feature, how
do you feel that this proposal compares to those?
Yes Scala, Haskel, and Java

• How much effort did you put into your review? A glance, a quick reading,
or an in-depth study?
Participated in Swift Evolution discussion

  -- Howard.

On 8 November 2017 at 10:23, John McCall <rjmccall at apple.com> wrote:

> Hello, Swift community!
>
> The review of "SE-0187: Introduce Sequence.filterMap(_:)" begins now and
> runs through November 14th, 2017.  The proposal is available here:
>
> https://github.com/apple/swift-evolution/blob/master/
> proposals/0187-introduce-filtermap.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 me as the
> review manager.  When replying, please try to keep the proposal link at the
> top of the message:
>
> Proposal link:
>
> https://github.com/apple/swift-evolution/blob/master/
> proposals/0187-introduce-filtermap.md
>
> Reply text
>
> Other replies
>
> *What goes into a review?*
>
> The goal of the review process is to improve the proposal under review
> through constructive criticism and, eventually, determine the direction of
> Swift.
>
> When writing your review, here are some questions you might want to answer
> in your review:
>
> • What is your evaluation of the proposal?
> • Is the problem being addressed significant enough to warrant a change to
> Swift?
> • Does this proposal fit well with the feel and direction of Swift?
> • If you have used other languages or libraries with a similar feature,
> how do you feel that this proposal compares to those?
> • How much effort did you put into your review? A glance, a quick reading,
> or an in-depth study?
>
> More information about the Swift evolution process is available at:
>
> https://github.com/apple/swift-evolution/blob/master/process.md
>
>
> As always, thank you for contributing to the evolution of Swift.
>
> John McCall
> Review Manager
>
> _______________________________________________
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> swift-evolution-announce at swift.org
> https://lists.swift.org/mailman/listinfo/swift-evolution-announce
>
>
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