[swift-evolution] Two thoughts on concurrency

Chris Lattner clattner at nondot.org
Thu Aug 24 22:58:18 CDT 2017


> On Aug 24, 2017, at 8:57 PM, Chris Lattner via swift-evolution <swift-evolution at swift.org> wrote:
> 
> On Aug 24, 2017, at 1:59 PM, Dave DeLong via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
>> Keyword Explosion
>> 
>> During the Great Access Control Wars of Swift 4, one of the points that kept coming up was the reluctance to introduce a bazillion new keywords to address all the cases that were being brought up. The impression I got is that adding new keywords was essentially an anti-pattern. And so when I’m reading through this onslaught of emails, I’m troubled by how everything is seeming to require new keywords. There’s the obvious async/await, but there’s also been discussion of actor, reliable, distributed, behavior, message, and signal (and I’ve probably missed others).
> 
> I can’t speak for message/signal, but you need to understand a bit more about how Swift works.  There is a distinction between an actual keyword (which ‘async’ would be, and ‘class’ currently is) and “modifiers”.  Modifiers occur with attributes ahead of a real keyword, but they are not themselves keywords.  They are things like weak, mutating, reliable, distributed, etc.  If we go with the “actor class” and “actor func” approach, then actor would not be a keyword.

Concrete example, this is (weird but) valid code:

var weak = 42
weak += 2
print(weak+weak)


This is a consequence of weak not being a keyword.

-Chris


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