> On May 10, 2016, at 4:57 PM, Rob Napier via swift-evolution 
> <[email protected]> wrote:
> 
>> On Tue, May 10, 2016 at 2:53 PM, Chris Lattner via swift-evolution 
>> <[email protected]> wrote:
>> 
>>         * What is your evaluation of the proposal?
> 
> Trailing commas is clearly very useful in the collections case. While that 
> case is more common than functions and tuples, I don't see any reason that 
> collections should be treated as a special case. Why should some 
> comma-separated lists allow trailing commas and some not?
> 
> This seems a reasonable move towards consistency and is useful in some cases 
> while not harmful in others. When in doubt, I'd rather broad rules ("trailing 
> commas are allowed in comma-separated lists") rather than special cases. This 
> improves teachability.

If one look purely at commas, the inconsistency may be hard to explain, but if 
one include the enclosing characters there are clear rules:

- within square brackets: trailing comma allowed
- within parenthesis: trailing comma not allowed
- within angle bracket: trailing comma not allowed

Weird, I do not recall anyone mentioning generics in the original trailing 
comma thread.

Dany

> 
> It also improves diffs when functions pick up new parameters, particularly 
> ones with default values. This is particularly common (and expected) in 
> constructors. That's valuable.
> 
>  
>>         * Is the problem being addressed significant enough to warrant a 
>> change to Swift?
> 
> As a language rule simplification, I believe it's worth a change if it 
> doesn't introduce problematic corner cases. The fact that it improves diffs 
> is no less valuable for functions than it is for collections.
> 
>  
>>         * Does this proposal fit well with the feel and direction of Swift?
> 
> Yes; it definitely feels Swifty in the same way that it does for collections. 
> There's no reason for Swift to treat them differently.
> 
>  
>>         * If you have used other languages or libraries with a similar 
>> feature, how do you feel that this proposal compares to those?
> 
> I've seen this in Perl, Python, and Go. Basically every language I've used 
> that allows trailing commas in collections also allows them in function 
> calls. In Go, the trailing comma is mandatory in some cases. This has been 
> nice for consistency.
> 
>  
>>         * How much effort did you put into your review? A glance, a quick 
>> reading, or an in-depth study?
> 
> Quick reading.
> 
> -Rob
> 
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