[Draft] Adding Safe indexing to Array

[CTMacUser (Daryle Walker)]

@QuinceyMorris

However…

There’s yet another possible direction, which is to stop thinking of the parameter as an index (valid or invalid), but rather as an offset from the start of the array, which kind of links this thread up with this other thread: Shorthand for Offsetting startIndex and endIndex.

The various suggestions in that thread are mostly about slicing, so don’t necessarily propose a single-argument lookup method/subscript, and those that do provide a non-optional result. I suppose they could have an optional result instead, since this is not a vital case in that proposal.

The advantage would be a single, consistent keyword convention (whether method or array), that “explains” the optional return type in terms of a semantic difference in the parameter type (index vs. offset), even though both types are Int for an array.

The optional result doesn’t quite “sit” naturally in that thread, but I don’t see all that much consensus emerging in this thread. A joint solution might be more palatable.

Yes. This other thread and its offset ideas were what I was thinking of in my last reply here.