> Am 16.10.2017 um 17:49 schrieb Jonathan Hull via swift-evolution 
> <swift-evolution@swift.org>:
> 
> 
>> On Oct 16, 2017, at 7:20 AM, Xiaodi Wu <xiaodi...@gmail.com 
>> <mailto:xiaodi...@gmail.com>> wrote:
>> 
>> To start with, the one you gave as an example at the beginning of this 
>> discussion: Two sets with identical elements which have different internal 
>> storage and thus give different orderings as sequences.  You yourself have 
>> argued that the confusion around this is enough of a problem that we need to 
>> make a source-breaking change (renaming it) to warn people that the results 
>> of the ‘elementsEqual’ algorithm are undefined for sets and dictionaries.
>> 
>> No, I am arguing that the confusion about ‘elementsEqual’ is foremost a 
>> problem with its name; the result of this operation is not at all undefined 
>> for two sets but actually clearly defined: it returns true if two sets have 
>> the same elements in the same iteration order, which is a publicly 
>> observable behavior of sets (likewise dictionaries).
> 
> But that iteration order is undefined and could easily change due to changes 
> in the private/internal structure of sets/dictionaries.  Algorithms that rely 
> on that “publicly observable behavior” (i.e. leaking of internals) will 
> suddenly break.  You keep claiming that this bug is a feature because it is 
> the current behavior… but that is tautological reasoning.

Indeed.

-Thorsten

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