[vbezhenar]

I've used Kotlin quite a bit as a Java replacement in the past. However its roadmap was weird for me. I wanted Kotlin to be a thin layer upon Java, however Jetbrains ported it to JavaScript, to native. It felt like lack of focus. Another issue with Kotlin was, that its development did not 100% align with Java. Kotlin co-routines were invented, but Java went into green threads direction instead, so this feature feels like unnecessary complication of already complicated language.

Nowadays I prefer Java. It's not ideal, but it aligns 100% with JVM. Kotlin was good in Java 7 times, when Java development felt frozen.

[aarroyoc]

One important focus for Kotlin is mobile app development. However if you're just a thin layer over Java you can't create iOS apps, that's the whole story behind Kotlin Native/Kotlin Multiplatform. Being able to have apps that share code between Android and iOS. On the other hand I think a good Kotlin Native backend could be a great language in the Go space. Scala Native and Jank (Clojure) show that some people want a JVM less version of them. But currently Native is less performant than the JVM version. And now there's GraalVM, which is the Java solution for AOT and Kotlin could use it too. But it was invented after Kotlin Native.

The same thing with coroutines and virtual threads. Or with Kotlin data classes and Java records. Kotlin was first, Java then implements something to solve the same issue but it's not the same way as Kotlin.

[jillesvangurp]

> I think a good Kotlin Native backend could be a great language in the Go space

With Ktor there is the beginnings of that. It can actually compile to native; but with some limitations. There's also the web assembly compiler which would make sense for things like server less and edge computing type use cases. Both are a bit neglected from a server side perspective by Jetbrains. But the potential is there. And the whole Kotlin native path could be a lot easier and more lightweight than dealing with Graal.

The weak spot for Kotlin native outside the IOS ecosystem is compiler maturity, the library ecosystem, and lack of support for system libraries (e.g. posix and WASI for wasm).

Those are fixable problems. But it's only partially there currently and I would not recommend it for that reason. However, I think the whole effort with IOS native has moved things forward quite a bit in the last two years. Getting Kotlin to the level of Go in terms of compilers, tools, performance, and libraries on Linux and wasm would be similar in scope. But a few years of focus on that could make a lot of difference. IMHO, Kotlin could be perfect as a system programming language with some effort.