alt Hacker NewsLocal type inference, records, and switch expressions (alongside lambdas and generics) are all ML features, as every language designer will tell you (and Java did them quite differently from Kotlin). All of them, by the way, were well known to Java's original designer in the nineties, it's just that they thought it will be a while until mainstream programmers are ready for them, so their adoption in Java is best postponed.
BTW, even if you're not aware of ML's extraordinary influence on most programming languages, surely you're aware there are competitors to Java with analogous features that are far bigger than Kotlin.
As for string templates, our intent is not to have a feature simiar to what Kotlin offers. We obviously look at all languages regardless of popularity, but in that case, as we did in the case of virtual threads or records, we'll probably say, no, that's not what we want, to Kotlin's approach (even the Preview that we pulled was nothing like Kotlin's approach).
> I'm sure there's tech-debt and esoteric compatibility concerns which make evolving Java hard
Backward compatibility is rarely a hindrance at all. People just talk about it a lot because most organisations consistently say that backward compatibility is much more important to them than any language feature, but it's not all that hard to maintain.
> but from a developer's perspective it's just glacial to evolve and the result is weaksauce.
I find that statement hard to reconcile with the fact that the only languages as popular as Java or more are JS/TS and Python, while all the languages that are not "weaksauce" from "a developer's perspective" are doing far, far worse than Java. There has never, ever, been any sort of consensus among developers on the right set of features, and there have always been developers who prefer more features and those who prefer less. It's perfectly fine to be on one side or the other or even to say, "yes, I'm in the minority, but I still think I'm right", but I find it strange to claim to represent "the developer's perspective" when your preferences are mostly associated with languages that are doing worse rather than better.
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I get your point, but Kotlin is still what made many of these specific features widely known to java developers, and accelerated the push from devs to get similar things into java.
Mind you, I like that java has taken its time to get the features right. Of course, java has had the advantage of enhancing the jvm while adding the features, where Kotlin had to work around the jvm in some cases (like green threads vs coroutines).
So I prefer javas version of many of the of the more modern things (but do miss Kotlin's lambdas and vast library of extension functions when writing java). But I feel it's wrong to downplay Kotlin's role in modernizing things on the jvm. Heck, if it weren't for kotlin as a temporary stopgap, I'd probably would've left the jvm while the features were still lacking in java.