[swift-evolution] ? suffix for <, >, <=, >= comparisons with optionals to prevent subtle bugs

[Kevin Ballard]

I completely disagree. Being able to compare `Optional` values is very
handy in a lot of cases. Adding special syntax for this is just
unnecessary language complication, especially as the proposed syntax
conflicts with the existing meaning of the postfix-? operator and the
optional-chaining operator.

-Kevin Ballard

On Thu, Dec 3, 2015, at 04:17 PM, Jacob Bandes-Storch wrote:
> Agreed — or, I think, these operators could/should simply be removed.
>
> I filed <rdar://22833869> about this a while ago, which was marked as
> Duplicate/<rdar://16966712>.
>
>> Summary:
>>
>> This returns true:
    (nil as Int?) < 0 This also returns true, which makes even less
    sense: (nil as Int?) < Int.min
>>
>>
>> Expected Results:
>>
>> nil < 0, nil > 0, and nil == 0, should all be false. nil != 0 should
>> be true.
Alternatively, just *don't* provide < and > operators that accept
optional arguments.
>>
>>
>> Actual Results:
>>
>> nil < 0 is true. Others are as expected.
>>
>
>
> See also: https://twitter.com/jtbandes/status/646914031433871364
>
>
> Jacob
>
> On Thu, Dec 3, 2015 at 3:42 PM, Amir Michail <a.michail at me.com> wrote:
>> Such comparisons with optionals can result in hard to find bugs.
>>
>>
For example consider:
>>
>>
let f = x < 5  // x is of type Int? and may be nil
>>
>>
The proposed ? suffix would be used as follows and makes the possibility
of nil very clear:
>>
>>
let f = x? < 5
>>
>>
>>
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