[swift-evolution] Remove (!) logical negation operator

[Andrew Brown]

I'm interested to hear what the opinions are for this.
When I first read the idea I was a definite NO! (See what I did there :) )
But after thinking about it I'm interested to hear how people feel about this.
The obvious issue is what do we do with '!=' ?
Most languages which do not use ! for negation use '<>' for '!=' and I'm no sure how popular that would be.

ABR.

> On 15 Dec 2015, at 15:01, Marc Knaup via swift-evolution <swift-evolution at swift.org> wrote:
> 
> I'm uncertain but it's definitely worth considering.
> 
> I also think that it's weird at the moment since in most cases the exclamation mark is now something dangerous.
> I also had a couple of bugs in my code because the operator is too easy to miss and the negation was not or no longer intended.
> 
>> On Tue, Dec 15, 2015 at 3:11 PM, Bruno Berisso via swift-evolution <swift-evolution at swift.org> wrote:
>> Hello,
>> 
>> I'm really used to negate logical expressions with this operator but it never feels confortable to me. If I need to negate some complex expression sometimes I prefer to write a temporal variable and then negate that with ! because I fear than others, or myself, could overlook it and cause confusion.
>> 
>> Now that Swift use the same operator to force the unwrap of optional values it becomes even worse.
>> 
>> Consider this examples:
>> 
>> if someOptionalValue != nil {
>>     ...
>>     if !(otherBoolValue && someOptionalValue! > 0) {
>>         ...
>>     }
>> }
>> 
>> Or even worse, what happen when negating Optional<Bool> values?
>> 
>> //Best case
>> if let value = optionalBool where !value {
>>     ...
>> }
>> 
>> //Worse case
>> if !optionalBool! {
>>     ...
>> }
>> 
>> Now what happen with this examples if we instead use a not operator:
>> 
>> if someOptionalValue != nil {
>>     ...
>>     if not (otherBoolValue && someOptionalValue! > 0) {
>>         ...
>>     }
>> }
>> 
>> if let value = optionalBool where not value {
>>     ...
>> }
>> 
>> if not optionalBool! {
>>     ...
>> }
>> 
>> I'm not sure if not is the right path here but I really want to improve the ! to something more clear at a glance and that doesn't have different behaviour depending where it appears in an expression.
>> 
>> Thanks,
>>  
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> 
> 
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