<div dir="ltr">I had read the discussion live as it happened. And just now I went back to see Jaden’s posts again: there are only a handful, and all are quite brief. To the extent that they “sketched a direction”, I would say no. We should instead base the proposal on ideas laid out by Dave Abrahams, Brent Royal-Gordon, Ben Cohen and several others.<div><br></div><div>Furthermore, we emphatically do *not* need to make the distinction you claim between “infinite” and “incomplete” ranges, which *is* needless hairsplitting.</div><div><br></div><div>We (meaning Swift Evolution) can define any semantics we like for any operator we like. The simple, elegant, intuitive behavior for one-sided ranges is exactly the “do what I mean” approach as described by many people including Dave Abrahams.</div><div><br></div><div>Want to subscript a collection using a one-sided range? Great! If the fixed bound is inside the collection then go as far as possible (ie. from start or to end), and if it is outside then trap for index out of bounds.</div><div><br></div><div>Want to zip together integers and sequence elements? Great! If the sequence eventually ends then stop when it does, and if not then trap when the integer overflows.</div><div><br></div><div>Want to iterate over a one-sided range? Well if the upper end is open then great! “for i in 20...” will loop until it hits a “break” or trap on overflow. We could probably even make “for i in (...20).reversed” work and count down, though we don’t have to.</div><div><br></div><div>In any case, the point remains: if we do add one-sided ranges, we can define any behavior we want for them. And given the opinionated nature of Swift, it follows that we should choose to make them expressive, useful, and enjoyable.</div><div><br></div><div>Nevin</div><div><br></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Wed, Feb 1, 2017 at 10:58 AM, Matthew Johnson <span dir="ltr"><<a href="mailto:matthew@anandabits.com" target="_blank">matthew@anandabits.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><span class=""><br>
> On Feb 1, 2017, at 9:52 AM, Nevin Brackett-Rozinsky <<a href="mailto:nevin.brackettrozinsky@gmail.com">nevin.brackettrozinsky@gmail.<wbr>com</a>> wrote:<br>
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> Drafting a proposal sounds like a good idea, to establish all the relevant information in one place. I don’t recall off the top of my head what directions Jaden sketched out, but as long as the proposal hits the high points of the uses and benefits, and summarizes the discussion and alternatives, it should be fine.<br>
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> I might suggest using Chris’s terminology of “one-sided range”, because that is both more precise and it renders moot all the “incomplete” vs “infinite” hairsplitting.<br>
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</span>I recommend reading through the discussion Xiaodi and I had yesterday, which Jaden chimed in on. We really do need to make a distinction between incomplete and infinite ranges if we want to support all of the use cases with clean semantics. This isn’t hair splitting.<br>
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> Nevin<br>
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