`for inout` loop

[oscbyspro]

There's a pitch related to Swift's ownership model for mutating iterated collection's elements in-place. I do it a lot in this package, so I'm looking forward to it. The gist of it is replacing the first with the second example:

var index = words.startIndex
while index < words.endIndex {
    mutate(&words[index])
    words.formIndex(after: &index)
}

for inout word in words {
    mutate(&word)
}

[oscbyspro]

That said, I'm also iterating backwards and dunno if that will be supported.

[oscbyspro]

I suppose this is a closer comparison. I've just gotten used to while loops because they are always fast, whereas I feel like I have to performance profile each instance of .reversed().

for index in words.indices {
    mutate(&words[index])
}