I understand that that's your thinking. I just don't understand how you arrived at your rule (2). It's not in the dictionary definition of the words prefix and suffix. Nor do I find any documentation of such a rule in Swift. Nor do I think you've shown that such a rule is necessary for clearing up some actual confusion. Nor do I see that applying the rule and using subscripts yields a superior solution to what we currently have. On Tue, Jun 28, 2016 at 5:40 PM Brent Royal-Gordon <br...@architechies.com> wrote:
> > I was in the midst of writing a reply along the same lines, so I figured > I'd add to David's reply here. There are two characteristics I would expect > from a method named "prefix" or "suffix". > > > > First, it should return a subsequence containing zero to count elements. > (By contrast, something named "first" should return nil or one element, but > certainly no more.) > > > > Second, in the case of "prefix", the first element of the subsequence > (if any) should be the first element of the sequence; in the case of > "suffix", the last element of the subsequence (if any) should be the last > element of the sequence. > > I would phrase these things slightly differently. In my thinking, a method > with `prefix` or `suffix` in its name: > > 1. Operates on a subsequence at the beginning/end of the sequence, > > 2. Measured *relative* to the beginning/end. > > An index-based operation doesn't fit this definition because an index is > not *relative* to anything—it's an *absolute* position within the sequence. > > Put another way, in my view, "prefix" and "suffix" don't merely mean > "anchored at the beginning/end". A prefix or suffix is attached to a > "middle". There is no middle in the index-based operations. > > It is, of course, very possible to use methods to express what the > index-based operations do: > > friends.upTo(i) > friends.through(i) > friends.from(i) > > But at this point, we've basically arrived at `friends[to: i]` etc. > > -- > Brent Royal-Gordon > Architechies > >
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