[swift-evolution] [Idea] return if / return unless

[David Rönnqvist]

One complication with allowing postfix conditionals for all statements is that it often needs to have an else clause as well (like the ternary operator “?:").

For example, what’s the type of “x” below?

let x = 5 if someCriteria()

And is “y” initialized or not?

let y: Int
y = 42 if someCriteria()
doSomething(with: y)

I realize that this idea is more about the feature/behavior than the naming, but renaming “guard” to “unless” is one of the commonly rejected proposals.
https://github.com/apple/swift-evolution/blob/master/commonly_proposed.md

- David


> On 04 Aug 2016, at 16:52, Kurt Werle via swift-evolution <swift-evolution at swift.org> wrote:
> 
> Why would you do this just for return statements?  Why not do postfix conditionals for all statements (like ruby)?
> 
> I've always liked postfix conditionals, but not enough to suggest them.  Mostly I'm curious about limiting the scope to return statements.
> 
> On Thu, Aug 4, 2016 at 7:31 AM, Christian Kienle via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
> +1
> 
> 2016-08-04 15:38 GMT+02:00 Julian Dunskus via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>>:
> How often have you written something like the following?
> 
> `
> if indexPath.row == 0 { return }
> 
> guard let thing = things[index] else { return nil }
> `
> 
> I propose adding some syntactic sugar to make such statements more readable and simple to write:
> 
> `
> return if indexPath.row == 0
> 
> return nil unless let thing = things[index]
> `
> 
> I don’t know how easy or hard this would be to implement, but I think it would improve some code significantly.
> 
> –Julian Dunskus
> 
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> 
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