Go and Rust are interesting to follow. A highish and low level language both using lightweight runtimes

Smalltalk is exactly like that - other objects' state is only mutable through explicit message passing. It's also widely considered the penultimate pure OO language.

> Pretty much all of the OO languages are walking back OO features

About the only feature I can think of for which this is somewhat true is inheritance, and that's because we realized that aggregation is often a better model, and can be easily supported by the language to be no more verbose. But it doesn't fundamentally change OO - it was never about inheritance first and foremost; I mean, prototype-based OO doesn't even have that conceptually.

> and trying to add type classes (contracts)

In most OO languages, these typically naturally evolve out of interfaces.

> functional pieces, mapping and filtering a la linear data transformations.

This is not contradictory to OO in any way. Again, Smalltalk has had "select" (filter) and "collect" (map) from the get go.

Lombok makes immutable data classes trivial. Improved interface support for default methods make it possible to largely ignore OO if you don't want it.

FP is mostly a community effort at this point, but solid. Java Streams are decent for basic stuff like map/filter but RXJava is extremely powerful if you want the complexity it comes with. Vavr is nice for adding more FP types too

You can also compile AOT for some performance loss at runtime but zero startup time. Android has been doing this forever but you can also do it on a PC using Graal.

And yes Java will destroy Erlang at concurrent connections if you use an async framework like Vert.X or fibers using Quasar/Comsat. It has lower per thread overhead than Erlang and runs code faster in general.

Both Java and Erlang will max out Linux TCP connections before running out of steam so this is kinda academic though

I don't drool over the raw horsepower of each of my individual boxes.[1] All I care about is that I can cost effectively create a cluster of them to serve the application's needs.

Because of this, even if Java could not handle as many concurrent connections, you might still chose it over this fabled 10M socket erlang server you keep talking about.

You might chose Java because:

* It is well understood and has a lot of mature libraries surrounding it.

* You can easily hire people to work on it.

* It is a stable language.

And so on...

I would summarize your original post like this: "I don't like Java, I prefer other things," which is fine as far as it goes, but then you basically say: "Therefore, everyone should also prefer the same things I do," which does not follow.

[1] I never particularly cared how many fps I can get on my machine, and I'm not that chuffed about my machine's geekbench score. IMHO this obsession with hardware metrics beyond diminishing returns is mostly a gamer thing.