Erlang vs. Scala

You can run Erlang on JVM it's called Erjang [1].

The author of the project claim, that with time Erjang will be better/faster than Erlang, since JVM getting improved faster, than standard Erlang VM - BEAM.

[1] http://www.javalimit.com/2009/12/erjang-why.html

Akka has a Java API, too.

I thought that Akka was going to be the missing link on Scala also. So I started investigating and building, and ran into some roadblocks. In particular, I found that Scala offers actors, but the distributed and highly available cluster aspects that Erlang's OTP offers were missing from Scala. Akka looks like it's going to provide this, at first blush. But after further investigation, it doesn't really provide that, yet, at least it didn't last I checked.

So I posted this question on StackOverflow and on the Akka mailing list:

http://stackoverflow.com/questions/3692680/scala-akka-how-to...

The question is about how you build fault tolerance, such that your cluster has no single point of failure. At the time, the principal authors of Akka responded saying that you can't right now out of the box, and they're working on that for a later commercial release.

Since then I started looking at integrating Scala + Zookeeper, and more seriously considered Go + Zookeeper, and it revived my interest in Erlang.

The closest thing Erlang has to mutability is the process dictionary (get() and set()), which can be thought of as a sort of memcache for each process. Native variables themselves are immutable, without exception.

Unless you have a really good reason, using the process dictionary is generally frowned upon.

Immutability being possible is not the same as mutability being impossible (or the rare exception that is dealt with in a special manner).

His point is that since in Scala mutability is possible (and indeed is idiomatic) you run into concurrency concerns.