[swift-evolution] Optional safe subscripting for arrays

[David Sweeris]

Actually, I just thought of another setter problem: everything talked about so far allows you to assign a 'Element?', which can ignored in the setter (and is in some of the code snippets I posted), but assigning 'nil' really should be a compile-time error.

Should this be split into two proposals (one for getter and one for setter), or is that premature?

- Dave Sweeris