[swift-evolution] State of @noescape ?

Антон Жилин antonyzhilin at gmail.com
Mon Jun 20 12:55:09 CDT 2016

IIRC, there were at least the following counter-arguments:
1. One must break API and ABI compatibility to add @escaping to an existing
2. @nonescaping case is actually quite as common as @escaping

Frankly speaking, I support both of this arguments. I'll also add another

Lazy map and filter will be marked as @escaping. Now consider the following

func sum<T>(_ array: [T], transform: (T) -> Int) -> Int {
    return array.lazy.map(func).reduce(0, combine: +)

`transform` will be marked as @escaping, despite that `transform` never
actually escapes `sum`.

I believe that we should not accept nonescaping-by-default until we get a
powerful lifetimes system, as in Rust.

I think it makes sense to create a mini-proposal just for renaming of
@noescape to @nonescaping.

- Anton

2016-06-20 20:37 GMT+03:00 Austin Zheng <austinzheng at gmail.com>:

> Trent Nadeau had prepared a proposal on Chris Lattner's recommendation,
> and there was a discussion thread a few weeks back:
> http://thread.gmane.org/gmane.comp.lang.swift.evolution/19756.
> Not sure what the outcome was. I don't see any open PRs to merge the
> proposal into the swift-evolution repo.
> Austin
> On Mon, Jun 20, 2016 at 9:06 AM, Антон Жилин <swift-evolution at swift.org>
> wrote:
>> Hmm, I guess you are right, there would be no point keeping @nonescaping,
>> then.
>> - Anton
>> 2016-06-20 18:55 GMT+03:00 David Waite <david at alkaline-solutions.com>:
>>> On Jun 20, 2016, at 9:39 AM, Антон Жилин via swift-evolution <
>>> swift-evolution at swift.org> wrote:
>>> * Rename @noescape to @nonescaping, and make @nonescaping the default
>>> case
>>> Do you mean replace @noescape with its opposite, @escaping?
>>> -DW
>> _______________________________________________
>> swift-evolution mailing list
>> swift-evolution at swift.org
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