[swift-evolution] [Draft] Hasher & HashVisitable

Vladimir.S svabox at gmail.com
Tue Mar 14 12:00:06 CDT 2017

On 14.03.2017 18:34, Joe Groff via swift-evolution wrote:
>> On Mar 13, 2017, at 10:54 AM, Sean Heber via swift-evolution
>> <swift-evolution at swift.org> wrote:
>> I’m dumb when it comes to proper hashing, but it’s such a tediously
>> common thing in my experience to need to add Hashable to some kind of
>> a struct so I can stash it in a set or use it as a dictionary key. Is
>> there really no way to make this all more automatic? I have to be
>> honest - this proposal seems *harder* to understand than the way it
>> works now. Of course the easiest would be if the language could just
>> do this “good enough" for me using reflection or whatever and if I
>> really did run into a problem where I wanted to do this myself, I
>> could override something.
>> Perfect is the enemy of good.
> The compiler totally ought to derive reasonable default Equatable and
> Hashable implementations for you. That would allow the standard library
> to do the right thing without burdening most users with the need to
> sweat the details.

I believe many of us dream of an feature of auto-generated Equatable and 
Hashable implementations.

Btw, what is your opinion, can we expect (at some point of time) 
Equatable&Hashable for tuples?
It is very handy to have Dictionary<Tuple<type1,type2>, type3> in C# and 
sad that we can't have [(type1,type2):type3] in Swift without declaration 
of new temporary struct type and implement Equatable&Hashable for it.

> -Joe _______________________________________________ swift-evolution
> mailing list swift-evolution at swift.org
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