[swift-evolution] Strings in Swift 4

[Jaden Geller]

> On Jan 31, 2017, at 11:26 AM, Dave Abrahams <dabrahams at apple.com> wrote:
> 
> 
> on Mon Jan 30 2017, Jaden Geller <jaden.geller-AT-gmail.com> wrote:
> 
>>> On Jan 30, 2017, at 11:35 AM, Dave Abrahams via swift-evolution <swift-evolution at swift.org> wrote:
>>> 
>>> Why should that be out-of-bounds?  Whether it is out-of-bounds would
>>> depend on what items is.  If it's an array, that should be equivalent to
>>> 
>>>  let x = items[items.startIndex..<items.endIndex]
>> 
>> It seems to me that `items[0…]` would be equivalent to
>> `items[0…Int.max]` if we’re going to treat `0…` as an “infinite"
>> range, no? Otherwise, we’re either giving subscript of InfiniteRange
>> types special behavior or we’re making subscript ignore past-the-end
>> indices; `”hello”.characters[0…10]` would need to return the same as
>> “hello”.characters[0…4]` to be consistent.
> 
> What is it they say about “a foolish consistency?” ;-)
> 
> More seriously, I think you may be viewing these ranges the wrong way
> around.
> 
>    0...
> 
> is not a range with an upper bound of infinity (which is, after all, not
> a number!); it's a range with *no* upper bound.  When you use the range
> for slicing, the collection substitutes its own upper bound.
> 
> HTH,
> 
> -- 
> -Dave

I think that is perfectly reasonable, but then it seems weird to be able to iterate over it (with no upper bound) independently of a collection). It would surprise me if
```
for x in arr[arr.startIndex…] { print(x) }
```
yielded different results than
```
for i in arr.startIndex… { print(arr[i]) } // CRASH
```
which it does under this model.