[swift-users] try? works on non-method-call?

[Nicholas Outram]

The issue is related to the as? 

Try this:

if let a = try? couldFailButWillNot()  {
   print(a)
}


Nick

> On 21 Jul 2016, at 07:13, Sikhapol Saijit via swift-users <swift-users at swift.org> wrote:
> 
> Hi Swift Community,
> 
> 
> Yesterday I tried this code:
> 
> ```
> func couldFailButWillNot() throws -> Any {
>   return 42
> }
> 
> if let a = try? couldFailButWillNot() as? Int {
>   print(a)
> }
> ```
> 
> And was surprised that the output was "Optional(42)” on both Swift 2.2 and Swift 3.
> I always have the impression that when a variable is resolved with `if let` it will never be optional.
> 
> So, with a little investigation, I found out that it happens because `as?` has higher precedence than `try?` and is evaluated first.
> And the whole expression `try? couldFailButWillNot() as? Int` evaluated as “Optional(Optional(42))”.
> 
> Also, I’m surprised that `try?` can be used with non-method-call.
> This code: `print(try? 42)` will print “Optional(42)”.
> 
> So, the questions are:
> 
> 1. Is it intentional that `try?` can be used with non-method-call and return an optional of the type that follows?
> 
> 2. Should we design `try?` to have higher precedence than `as?`. 
> My intuition tells me that 
> `let a = try? couldFailButWillNot() as? Int`
> and 
> `let a = (try? couldFailButWillNot()) as? Int` 
> should be equivalent.
> 
> 3. Do you think that doubly-nested optional (or multi-level-nested optional) is confusing and should be removed from Swift? (Yes, I’ve seen this blog post [Optionals Case Study: valuesForKeys](https://developer.apple.com/swift/blog/?id=12 <https://developer.apple.com/swift/blog/?id=12>))
> For me “Optional(nil)” (aka “Optional.Some(Optional.None))”) doesn’t make any sense at all. 
> Maybe, one of the solution is to always have optional of optional merged into a single level optional? Like Optional(Optional(Optional(42))) should be the merged to Optional(42).
> 
> 
> Thank you
> Sikhapol Saijit (Sam)
> iOS Developer, Taskworld, Bangkok
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> swift-users at swift.org
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