> In fact the most popular language for parallel and distributed programming is Erlang — a functional language.
Erlang achieves its parallelism not through immutability (though it has that) but through a shared-nothing architecture, like smalltalk. You can implement shared-nothing concurrency imperatively. It circumvents the problem of two threads accessing the same memory location by restricting access to only one thread. Of course, then there's the problem when you do need to share data between threads - Erlang does this with STM (software transactional memory - like a DB).
Erlang achieves its parallelism not through immutability (though it has that) but through a shared-nothing architecture, like smalltalk. You can implement shared-nothing concurrency imperatively. It circumvents the problem of two threads accessing the same memory location by restricting access to only one thread. Of course, then there's the problem when you do need to share data between threads - Erlang does this with STM (software transactional memory - like a DB).