[Draft] Adding Safe indexing to Array

[Jens]

@hooman

I have already told that I don’t like the idea, but if it ends up in the standard library, I agree that checked: is confusing as well. From @xwu’s suggestions, I can live with some form of if*. How about a[checking: i]?

I don't like it either, and I agree that some form of a[ifXxx: i] would be less confusing than a[safe: i] and a[checked: i]. I think a[checking: i] is almost as confusing as a[checked: i] (since it sort of implies that a[i] wouldn't be checking the index). Perhaps a[existing: i] ...

And IMHO the current proposal would actually add rather than remove an exception, as explained in my previous post. I think other options should be considered, like:

1. Using a subscript for a new type (eg SpecialArrayIndexThatIsCorrespondingToDictionarysKeyAndSetsElement, but sensibly named), for consistency with other collection types (again motivated by my previous post).

2. Using a method, eg a.element(ifExistingFor: Index) -> Element?