[swift-evolution] [Discussion] Breaking precedence

Anton Zhilin antonyzhilin at gmail.com
Mon Aug 1 17:01:24 CDT 2016


2016-08-02 0:52 GMT+03:00 Xiaodi Wu <xiaodi.wu at gmail.com>:

> On Mon, Aug 1, 2016 at 4:41 PM, Anton Zhilin via swift-evolution <
> swift-evolution at swift.org> wrote:
>
>> Disclaimer: I have not (yet) prepared a proposal, or even something that
>> could be considered a draft, but I want to hear public opinion on the topic.
>>
>> SE-0077 (about precedence groups) has been successfully implemented for
>> Swift 3. (A thousand thanks to John McCall!) It suggests a model where we
>> can prohibit certain operators from standing next to each other.
>>
>> This was intended to be the second part of that proposal. We now have to
>> think if we should drop some precedence relationships between standard
>> operators. Here are examples of parentheses dropping that can be ambiguous
>> to reader:
>>
>> 1/3 as Double   // should we prohibit this?
>>
>
> Why should we? I would absolutely want that to work exactly as it does now
> (0.333333...).
>

Strange enough, I've just run it and yes, 0.333333... But casting
precedence is lower than multiplicative, so I thought it would parse as
'(1/3) as Double'. Is it a bug?
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