I try to keep track of teams moving away from Scala at my company and among my friends and acquaintances, and I know a lot of key people in the community.
Scala to Kotlin stories are extremely rare.
Kotlin is almost non-existent in the data processing world (Spark, Flink, Kafka streams...)
Kotlin's presence in the average CRUD web app or more complex SOA doesn't overlap with Scala that much, as someone who enjoyed the paradigms available in Scala would definitely not move to Spring, and frameworks such as Ktor or http4k are pretty niche. I've seen people move to modern Java, Rust (a lot actually), even Go despite the language being at the other end of the spectrum. But Kotlin, not really.
Funny how experience differs. I think almost all Java teams I know use Kotlin now in some capacity, mostly for new code but sometimes for all code. Not to mention Android is a very large share of applications and Kotlin is the default choice there.
No Java teams at my company have moved to Kotlin. There’s a is a shift of Scala -> Java, I think many people are scared of adopting a guest language again and modern Java with records, switch expressions, and sealed types isn’t bad enough to warrant the risk.
Right, especially if you were burned by Scala, Kotlin is even less principled, and lately has grown in complexity, partly thanks to re-inventing several Scala features, only worse.
I also talk to pure Java teams, that never considered anything beyond the typical Java/Spring/Hibernate, they won't even have a look at slightly more modern approaches (Quarkus, Panache, build-time annotation processing and native images) despite jumping on new version of Java rather quickly. They couldn't care less about guest JVM languages.
Roughly speaking I believe that developers who enjoy Scala won't go a lesser language, that looks similar on the surface but specifically takes away what makes Scala special. Then people who dislike it will just stick to the most vanilla Java stack, which benefits from being literally one of the most popular choice on Earth.
Of course there are a few people doing Android or KMP, or who think Kotlin is in the right spot on the backend. But usually they aren't coming from Scala.
I don't enjoy Scala personally, but I do really enjoy Kotlin. It's a breath of fresh air to Java. WRT to spring -> Quarkus I think that's just a symptom of the teams being on a supported stack that works for them. There isn't necessarily anything wrong with Spring, unless you absolutely need the build time stuff. Thankfully I've managed to convince my own teams to move from Play to Quarkus.
How's that relevant to people moving away from Scala?
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