I agree that this behavior is annoying. However, wouldn’t it be source-breaking
to change this now?
-BJ
> On Jan 12, 2018, at 10:25 AM, Russ Bishop via swift-evolution
> <swift-evolution@swift.org> wrote:
>
> Greetings swift-evolution!
>
> There is currently a disconnect between optional chaining and try? when it
> comes to optional flattening:
>
>
> struct SomeType {
> func nonThrow() -> SomeType? { return self }
> func doThrow() throws -> SomeType? { return self }
> func nonOptional() throws -> SomeType { return self }
> }
>
> let w = SomeType().nonThrow()?.nonThrow()?.nonThrow()?.nonThrow()
> // w has type SomeType?
>
> let x = try?
> SomeType().nonOptional().nonOptional().nonOptional().nonOptional()
> // x has type SomeType?
>
> let y = try! SomeType().doThrow()?.doThrow()?.doThrow()?.doThrow()
> // y has type SomeType?
>
> let z = try? SomeType().doThrow()?.doThrow()?.doThrow()?.doThrow()
> // z has type SomeType??
>
>
> We get a double-optional only when combining try? and optional-chaining. That
> is inconvenient and it would be natural to have the compiler do the
> flattening here.
>
>
> If anyone is interested in working on the proposal or implementation please
> let me know. It would make a nice self-contained task if you're looking to
> start contributing.
>
>
> Russ Bishop
> Simulator
>
>
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