KEEP VS kotlin-multiplatform-bignum

Lenses work today. And I think the value class feature will be awesome.

https://github.com/Kotlin/KEEP/blob/master/notes/value-class...

Seems like Kotlin Context Receivers then (https://github.com/Kotlin/KEEP/blob/master/proposals/context-receivers.md).

Kotlin has value classes. Here's a good overview of how they work in Kotlin: https://github.com/Kotlin/KEEP/blob/master/notes/value-class...

That document is a few years old now and was intended as a design document. But Value classes shipped with Kotlin 1.5. Apparently they are compatible with the project Valhalla value objects that will be added to the JVM at some point. So, this stuff is coming.

I had to look it up because even though I write Kotlin a lot, value classes are not something I have used at all. Looks useful but not that big of a deal and doesn't really solve a problem I have. Data classes and records (in Java) are a bigger deal IMHO.

In practice, the way you deal with immutability in Kotlin is to keep most of your data structures immutable by default unless they need to be mutable. E.g. there's a List and a MutableList interface. Most lists are immutable unless you create a MutableList. Same with val vs. var variables. Val variables can't be reassigned and you kind of use var only by exception when you really have to. The compiler will actually warn you if you do it without good reason. A data class with only vals can't be modified. Java is a bit more sloppy when it comes to mutability semantics. It has records now but all the fields have setters by default. It has var but no val assignments (you can use final to force this but few people do). And so on.

Semantically this is not as strong as what Rust does of course but it's good enough to make e.g. concurrency a lot easier. Mostly, if you avoid having a lot of mutable shared state, that becomes a lot easier.

You could imagine a Kotlin like language with much stronger semantics implementing borrow checking instead of garbage collection. It wouldn't be the same language of course but I don't think it needs to be very different. Using it would not be a massively different.

I'd be very interested in a comparison between scala 3 using/given and Kotlin new context receivers https://github.com/Kotlin/KEEP/blob/master/proposals/context...

This will be furthermore simplified with multiple receivers coming very soon

Tfw no pattern matching. :(

I'm aware that kotlin decided against this in kotlin itself, see https://github.com/Kotlin/KEEP/issues/82.

If you like the idea of CoroutineScope, CoroutineContext, suspend, you will like the Kotlin Coroutines Design proposal https://github.com/Kotlin/KEEP/blob/master/proposals/coroutines.md

I've used this BigDecimal Kotlin implementation before and it seems to work fine, granted it would be nice if there was a alternative in the stdlib, but for now, that dependency works fine. :)