<div dir="ltr"><div class="gmail_quote"><div dir="ltr">On Fri, Jul 22, 2016 at 8:54 AM Dmitri Gribenko via swift-evolution <<a href="mailto:swift-evolution@swift.org">swift-evolution@swift.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">On Fri, Jul 22, 2016 at 8:38 AM, Nevin Brackett-Rozinsky<br>
<<a href="mailto:nevin.brackettrozinsky@gmail.com" target="_blank">nevin.brackettrozinsky@gmail.com</a>> wrote:<br>
> Excellent point Karl.<br>
><br>
> In my view, floating point NaN values are really quite similar to `.none`.<br>
><br>
> I would be interested in exploring a move *away* from the IEEE 754 handling<br>
> of NaN. In particular, we could model Float and Double as optionals (maybe<br>
> implicitly-unwrapped) with NaN bit-patterns indicating `.none`.<br>
><br>
> Or we could model *just the non-NaN values* and make undefined operations<br>
> trap, among other possibilities.<br>
<br>
I think these are non-starters.<br>
<br>
>>> 5. Will it be considered "ok" to define a type for which `T.areSame(a, b)<br>
>>> == true` but `a != b`? An obvious example would be Double.nan, so I assume<br>
>>> the answer is a resounding yes.<br>
>><br>
>><br>
>><br>
>> Yes, because `==` is not a protocol requirement of Equatable, so it<br>
>> can have domain-specific semantics.<br>
><br>
><br>
> Per SE-0091 the operator will be the protocol requirement.<br>
<br>
If SE-0091 removes non-protocol operators, then we will have to change<br>
the language again to accommodate what we need.<br></blockquote><div><br></div><div>SE-0091 does not (is not intended) to remove non-protocol operators. Global free operators can still exist; that proposal only clarifies the way that operator requirements within protocols manifest on conforming types (and how lookup is affected as a result).</div><div><br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<br>
Dmitri<br>
<br>
--<br>
main(i,j){for(i=2;;i++){for(j=2;j<i;j++){if(!(i%j)){j=0;break;}}if<br>
(j){printf("%d\n",i);}}} /*Dmitri Gribenko <<a href="mailto:gribozavr@gmail.com" target="_blank">gribozavr@gmail.com</a>>*/<br>
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</blockquote></div></div>