[swift-evolution] [Review] SE-0077: Improved operator declarations

[Matthew Johnson]

> On May 20, 2016, at 4:56 PM, Антон Жилин <antonyzhilin at gmail.com> wrote:
> 
> My working version is still the one in the proposal, but I'm planning to add the alternative versions we discussed, including your and Brent's variants.
> 
> IMHO, original version is heavy, but clear (not to confuse with "clean"). Your lighter version looks more clean, but somewhat less consistent and more free in terms of grammar.
> 
> Also, I've got another version, which is considerably ligher than current one, while being as structured:
> 
> precedence Multiplicative {
>     associativity(left)
>     above(Additive)
>     below(Exponentiative)
> }

In this case I think clear and clean are one and the same.  The parentheses feel arbitrarily noisy to me.  What purpose do they serve?

> 
> - Anton
> 
> 2016-05-21 0:25 GMT+03:00 Matthew Johnson <matthew at anandabits.com <mailto:matthew at anandabits.com>>:
> 
>> On May 20, 2016, at 4:22 PM, Антон Жилин <antonyzhilin at gmail.com <mailto:antonyzhilin at gmail.com>> wrote:
>> 
>> Yes, in this case it should be allowed, because this relationship already existed in imported modules. I will add that, too, thanks!
> 
> Cool.
> 
> What is the latest syntax you are using?  Did you consider any of the lighter weight options?  That subthread died without conclusion (unless I missed something somehow).
> 
> 
>> 
>> - Anton
>> 
>> 2016-05-21 0:01 GMT+03:00 Matthew Johnson <matthew at anandabits.com <mailto:matthew at anandabits.com>>:
>> 
>>> On May 20, 2016, at 3:51 PM, John McCall <rjmccall at apple.com <mailto:rjmccall at apple.com>> wrote:
>>> 
>>>> On May 20, 2016, at 1:25 PM, Антон Жилин <antonyzhilin at gmail.com <mailto:antonyzhilin at gmail.com>> wrote:
>>>> Inline:
>>>> 
>>>> 2016-05-20 20:58 GMT+03:00 John McCall <rjmccall at apple.com <mailto:rjmccall at apple.com>>:
>>>> The transitivity rule plus the ability to define precedence relationships in both directions on a new precedence group allows a new precedence group to create a precedence relationship between existing unrelated precedence groups.  This should be forbidden.
>>>> 
>>>> Agreed, although there is an alternate solution to allow global-scope relationship definition.
>>>> Trying to write it formally:
>>>> 
>>>> ====begin====
>>>> Precedence relationships that, by transitivity rule, create relationship between two imported groups, is an error. Example:
>>>> 
>>>> // Module X
>>>> precedencegroup A { }
>>>> precedencegroup C { }
>>>> 
>>>> // Module Y
>>>> import X
>>>> precedencegroup B { precedence(> A) precedence(< C) }
>>>> 
>>>> This results in compilation error "B uses transitivity to define relationship between imported groups A and C".
>>>> The rationale behind this is that otherwise one can create relationships between standard precedence groups that are confusing for the reader.
>>>> ====end====
>>> 
>>> Seems good to me.
>> 
>> Would this be allowed if Module X already defined precedence group C > A (it would not be defining a *new* relationship between A and C in that case)?
>> 
>>> 
>>>> What's the purpose of equality relationships between precedence groups?
>>>> 
>>>> Agreed, will remove.
>>> 
>>> Ok.
>>>  
>>>> Your proposal should call out the special treatment of the Assignment and Ternary groups.
>>>> 
>>>> Do you mean that most operators should define greater precedence than Assignment / Ternary? Or there should be some other special treatment?
>>> 
>>> Just that they have implicit members.
>>> 
>>> John.
>> 
>> 
> 
> 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.swift.org/pipermail/swift-evolution/attachments/20160520/29e34c20/attachment.html>