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

[Антон Жилин]

Sorry, "upper" and "lower" was my mistake that I copy-pasted all over the
place. Just in case, I added those alternate word variants, as well.

- Anton

2016-05-21 16:31 GMT+03:00 Matthew Johnson <matthew at anandabits.com>:

>
>
> Sent from my iPad
>
> On May 21, 2016, at 7:48 AM, Антон Жилин <antonyzhilin at gmail.com> wrote:
>
> Updated the proposal:
>
> https://github.com/Anton3/swift-evolution/blob/master/proposals/0077-operator-precedence.md
>
> I included many of alternate solutions. Please, reply, if I missed any.
>
> Still I do not hurry to swap any of alternate solution with syntax used
> throughout the proposal, although many of them are objectively better.
>
>
> Looks good.  I really hope we do go with one of the better syntax forms
> though.
>
> The one thing I don't like is "upper" and "lower".  Those don't make sense
> to me in this context.  Any of < and >, above and below, greaterThan and
> lessThan, gt and lt would be better IMO.
>
>
> - Anton
>
> 2016-05-21 1:17 GMT+03:00 Matthew Johnson <matthew at anandabits.com>:
>
>>
>> On May 20, 2016, at 5:06 PM, Brandon Knope <bknope at me.com> wrote:
>>
>>
>>
>> On May 20, 2016, at 5:56 PM, Антон Жилин via swift-evolution <
>> swift-evolution at swift.org> 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)
>> }
>>
>>
>> Why not:
>>
>> precedence Multiplicative {
>>     associativity left
>>     above Additive
>>     below Epxonentiative
>> }
>>
>>
>> Just seeing if removing the parens reduces some of the noise.
>>
>>
>> I would be happy with this.  It is almost the same as what I had
>> suggested, just using > and < rather than above and below (because that was
>> what the proposal was using).  Using words instead is fine with me.  The
>> parens are my biggest objection in this version.  In the original version I
>> also didn’t like the verbosity of `precedencegroup` and the redundant
>> statement `precedence` inside the braces.
>>
>>
>> Sorry if I missed this suggestion earlier and it was denied :P
>>
>> Brandon
>>
>>
>>
>>
>> - Anton
>>
>> 2016-05-21 0:25 GMT+03:00 Matthew Johnson <matthew at anandabits.com>:
>>
>>>
>>> On May 20, 2016, at 4:22 PM, Антон Жилин <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>:
>>>
>>>>
>>>> On May 20, 2016, at 3:51 PM, John McCall <rjmccall at apple.com> wrote:
>>>>
>>>> On May 20, 2016, at 1:25 PM, Антон Жилин <antonyzhilin at gmail.com>
>>>> wrote:
>>>> Inline:
>>>>
>>>> 2016-05-20 20:58 GMT+03:00 John McCall <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.
>>>>
>>>>
>>>>
>>>
>>>
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>>
>>
>>
>
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