I suspect most people feel it should be inclusive....

# announcements

[Mike]

I suspect most people feel it should be inclusive. I know I think that way. But obviously it's comfort and learning. Just like Java's substring takes time to learn. Generally people think it's inclusive of end index when it isn't.

[Dico]

I think the use case for inclusive ranges is WAY less common than exclusive ranges. I think it's a semantic decision assessing how best to distinguish between the two that resulted in this situation where most of the time you have to write until or a..b-1

Personally, I find it very frustrating, I think .. should represent an exclusive range because of the use case being so much more common. It's counter intuitive with the style of indices starting at 0 rather than 1.

But the window to change it has long faded.

[karelpeeters]

Nearly every range is exclusive, subList, random.nextInt, the most common for loop is 0, size exclusive, etc. I like what Rust did more, .. is exclusive and ..= is inclusive. Too late to change now 🤷‍♂️

[Mike]

I think we can agree that both are very common. It's whatever way you've decided to approach it, and subjective.

I also agree that the decision has been made.

[ghedeon]

I don't think it's too late. We just need to add <
Swift: 0...5 & 0..<5

I like it even more than Rust version

[Dico]

That's a great idea @ghedeon, I'm happy to help with a KEEP

[Dico]

@Mike when considering all languages, both might be common, I still think exclusive is more common though. But in kotlin, no, inclusive ranges do not compare to exclusive ranges in terms of how common they are. Moreover, I would never even use repeat function if this design were the other way around.

[Mike]

I’m not seeing connection between repeat and substring.

I’ve found people mess up substring in Java BECAUSE they think/assume it’s inclusive. So it’s opinion and YMMV situation all around.

I’m happy to learn whatever the language I’m using decides to have.

[karelpeeters]

repeat(10) { println(it) } is 0 to 10 exclusive too.

[Mike]

I wasn’t aware that repeat passed an index in… Obviously it would be non-intuitive if it was inclusive as it would repeat n+1 times.

[ghedeon]

@Dico could be something. Have you done this before? Any well written KEEP from the top of your head so we can follow the structure? Let's push it.

[Dico]

@ghedeon well I wrote this KEEP https://github.com/Dico200/KEEP/blob/ibd-enhancements/proposals/implementation-by-delegation-enhancements.md
But it hasn't had any answer from JB so probably not something to copy.

[Dico]

But the general structure is motivation and then solution in this case, and we're basically suggesting to add an operator fun until right?

[Dico]

@Mike the comparison is between repeat(10) { i -> and for (i in 0..10) {
I would prefer to write the latter, but the problem is that it's not the same. I'd have to write for (i in 0 until 10) { even though the exclusive range provided by until is a much more common use case.

[Dico]

@ghedeon This is probably a good place to start https://github.com/Kotlin/KEEP/blob/ac33aecff446a7affd8022f1d8b5a13e812837a4/proposals/stdlib/bignumber-operations.md

[Mike]

Personally, when I see 0..10, my brain instinctively thinks inclusive, so 0,1,2,…,10.

And now that I know repeat passes in the index, I wouldn’t be inclined to use for (i in 0..9) rather than repeat(10). But I agree it’s subjective, and support submitting a KEEP if you feel that strongly about it. Ultimately, it’s up to the Language team to decide.

[Dico]

We're not going to suggest changing it, that would break existing code. But something like ..< like @ghedeon suggested should be considered.

[karelpeeters]

@Dico Kind of off-topic but for what it's worth I really like that delegation proposal, there's a lot of good ideas in there that are very necessary. I hope it ends up getting somewhere.

[Dico]

Thank you @karelpeeters! ❤️