[swift-evolution] rethrows as first-class type annotation

[Jordan Rose]

John, IIRC you had some reason why this wasn't a great idea, but I can't remember it. It seems useful to me too, if not something that comes up too often.

Jordan

> On Dec 20, 2015, at 2:46 , Alexandre Lopoukhine via swift-evolution <swift-evolution at swift.org> wrote:
> 
> Hi Dmitri,
> 
> This is a better example than any that I have come up with so far as to why “rethrows” should be a part of the signature. You shouldn’t have to use “try!” to apply a non-throwing function, like {print($0)} to “forEach”.
> 
> — Sasha
> 
> 
>> On 20 Dec 2015, at 13:37, Dmitri Gribenko <gribozavr at gmail.com> wrote:
>> 
>> Hi Alexandre,
>> 
>> I think for this use case we don't actually need 'rethrows' to become
>> a part of the closure type, we just need the compiler to allow and
>> "instantiate" it in more places.
>> 
>> The case where we would need 'rethrows' to become a first class part
>> of the type system is if we wanted 'rethrows' to be a part of the
>> signature of the closure itself, for example:
>> 
>> (swift) let forEach = [ 10, 20, 30 ].forEach
>> // forEach : (@noescape (Int) throws -> Void) throws -> () = (Function)
>> 
>> Here, a more precise type would be (@noescape (Int) throws -> Void)
>> rethrows -> Void.
>> 
>> Dmitri
>> 
>> -- 
>> main(i,j){for(i=2;;i++){for(j=2;j<i;j++){if(!(i%j)){j=0;break;}}if
>> (j){printf("%d\n",i);}}} /*Dmitri Gribenko <gribozavr at gmail.com>*/
> 
> _______________________________________________
> swift-evolution mailing list
> swift-evolution at swift.org
> https://lists.swift.org/mailman/listinfo/swift-evolution

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.swift.org/pipermail/swift-evolution/attachments/20151221/ce204321/attachment.html>