I don’t know what the compiler does internally. However, I look at a signature like
func forEach(fn:Element throws->()) rethrows and imagine that conceptually this exposes two overloads for this “forEach” function: a) func forEach(fn:Element->()) b) func forEach(fn:Element throws->()) throws In fact, I expected the swift CLI to give me an error when I attempted to define all three of these as functions, but no such luck. -DW > On Dec 21, 2015, at 7:09 PM, Jordan Rose via swift-evolution > <[email protected]> wrote: > > 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 >> <[email protected] <mailto:[email protected]>> 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 <[email protected] >>> <mailto:[email protected]>> 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 <[email protected] >>> <mailto:[email protected]>>*/ >> >> _______________________________________________ >> swift-evolution mailing list >> [email protected] <mailto:[email protected]> >> https://lists.swift.org/mailman/listinfo/swift-evolution > > > _______________________________________________ > swift-evolution mailing list > [email protected] > https://lists.swift.org/mailman/listinfo/swift-evolution
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