[swift-evolution] Add unless/if single line syntax

[James Campbell]

If you implemented it the same way.  For me if we just had a unless which was the opposite an if it would be a better syntax than guard.

Sent from my iPhone

> On 14 Dec 2015, at 11:53, Etan Kissling <kissling at oberon.ch> wrote:
> 
> Sorry, 
> 
> return unless(username.text.characters.count > 0) {
>     return nil
> }
> 
> 
>> On 14 Dec 2015, at 12:53, Etan Kissling <kissling at oberon.ch> wrote:
>> 
>> It's not the same, OP wants to return nil.
>> 
>> So you have to write 
>> 
>> return unless(username.text.characters.count > 0) {
>>     return
>> }
>> 
>> and if you miss the first return, you just introduced a bug.
>> 
>> 
>> Etan
>> 
>>> On 12 Dec 2015, at 18:17, James Campbell via swift-evolution <swift-evolution at swift.org> wrote:
>>> 
>>> So 
>>> 
>>> guard username.text.characters.count > 0 else {
>>>         return
>>>     }
>>> could be expressed as 
>>> unless(username.text.characters.count > 0) {
>>>         return
>>>     }
>>> I think the second is much easier to read :)
>>> 
>>>> On Sat, Dec 12, 2015 at 4:28 PM, Al Skipp via swift-evolution <swift-evolution at swift.org> wrote:
>>>> Top marks!
>>>> 
>>>> unless(condition) { print("condition was false") }
>>>> 
>>>> The feature implemented in the language. What’s not to like?
>>>> 
>>>>> On 12 Dec 2015, at 16:20, Tommy van der Vorst via swift-evolution <swift-evolution at swift.org> wrote:
>>>>> 
>>>>> Oops, that should be just:
>>>>> 
>>>>> public func unless(expression: Bool, block: () -> ()) {
>>>>> 	if !expression {
>>>>> 		block()
>>>>> 	}
>>>>> }
>>>>> 
>>>>>> Op 12 dec. 2015, om 17:17 heeft Tommy van der Vorst via swift-evolution <swift-evolution at swift.org> het volgende geschreven:
>>>>>> 
>>>>>> Or, use something like this:
>>>>>> 
>>>>>> public func unless(expression: @autoclosure () -> Bool, block: () -> ()) {
>>>>>> 	if !expression {
>>>>>> 		block()
>>>>>> 	}
>>>>>> }
>>>>>> 
>>>>>> unless(..expression..) { 
>>>>>> 	...code...
>>>>>> }
>>>>>> 
>>>>>> /T
>>>>>> 
>>>>>>> Op 12 dec. 2015, om 17:08 heeft Al Skipp via swift-evolution <swift-evolution at swift.org> het volgende geschreven:
>>>>>>> 
>>>>>>> If at all possible I think it’s best to avoid adding keywords to the language. Instead of ‘unless', you could do: 
>>>>>>> 
>>>>>>> public func not(bool: Bool) -> Bool { return !bool }
>>>>>>> 
>>>>>>> if not(condition) { print("condition was false") }
>>>>>>> 
>>>>>>> Not terrible ¯\_(ツ)_/¯
>>>>>>> 
>>>>>>> 
>>>>>>>>> On 12 Dec 2015, at 15:48, Matthew Johnson via swift-evolution <swift-evolution at swift.org> wrote:
>>>>>>>>> 
>>>>>>>>> I’m not sure about the single line aspect of this proposal, but I am a big proponent of “unless” and “until” as complements to “if” and “while”.  They greatly improve readability over "if !(expression)” and “while !(expression)” IMHO.
>>>>>>>>> 
>>>>>>>>> On Dec 12, 2015, at 9:45 AM, Arthur Ariel Sabintsev via swift-evolution <swift-evolution at swift.org> wrote:
>>>>>>>>> 
>>>>>>>>> For your specific example, I'd 100% use the guard statement. It achieves the same result.
>>>>>>>>> 
>>>>>>>>> -1 from me.
>>>>>>>>>> On Sat, Dec 12, 2015 at 9:43 AM J. Cheyo Jimenez via swift-evolution <swift-evolution at swift.org> wrote:
>>>>>>>>>> -1 from me.  I think I would rather have an if-then expression that would handle both False and True cases. 
>>>>>>>>>> https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20151207/001944.html
>>>>>>>>>> 
>>>>>>>>>> Also, in most cases I feel that guard would be a better choice. 
>>>>>>>>>> 
>>>>>>>>>> 
>>>>>>>>>> 
>>>>>>>>>>> On Sat, Dec 12, 2015 at 5:39 AM, James Campbell via swift-evolution <swift-evolution at swift.org> wrote:
>>>>>>>>>>> I propose adding the unless and if statements from ruby.
>>>>>>>>>>> 
>>>>>>>>>>> Return false if james = nil
>>>>>>>>>>> 
>>>>>>>>>>> This returns false if the variable James is nil
>>>>>>>>>>> . This line does it unless james is nil:
>>>>>>>>>>> 
>>>>>>>>>>> Return false unless james = nil
>>>>>>>>>>> 
>>>>>>>>>>> This has been really handy when working in ruby, reduces lines and pyramids of doom
>>>>>>>>>>> 
>>>>>>>>>>> Sent from my iPhone
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>>>>>>>>>> 
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>>> 
>>> -- 
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