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

[Tommy van der Vorst]

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 <mailto: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 <mailto: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 <mailto: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 <mailto: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 <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 <mailto: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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