I do think that the status quo is good for try? precedence and such, but how
about the original problem? The code was hard to work with because it used a
double nested Optional. If you really don’t care about the reason that code
failed, then a single optional should be returned. There’s this:
if let rawA = try? couldFailButWillNot(),
let a = rawA as? Int
{
print(a)
}
…but it seems overly verbose. I think it would be easier if the standard
library included flatMap()’s companion, flattened() Optional<Optional<T>>, much
like the existing flatMap() and flatten() of Array<Array<T>>. Unfortunately,
this isn’t really possible:
extension Optional where Wrapped == Optional<T>
{
func flattened() -> Wrapped
{
if let wrapped = self
{ return wrapped }
else
{ return nil }
}
}
if let a = (try? couldFailButWillNot() as? Int).flattened() {
print(a)
}
…as the compiler complains that “T” is unresolved and that you can’t constrain
an extension with a generic type—or any non-protocol type, for that matter. A
free flattened() function would work, but wouldn’t be very clean or intuitive.
flatMap works for now, but isn’t great:
if let a = (try? couldFailButWillNot() as? Int)?.flatMap({$0}) {
print(a)
}
I guess that feature will have to wait until Swift 4._______________________________________________
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