[defined]

When I read about channels and various forms of IPC/inter-thread communication in most other languages, and remember the past pain of threads and mutexes in C/C++, I am so happy to be able to send a message in Erlang to another Erlang process (Pid) as easily as this:

    Pid ! {self(), 42}

And in the process identified by Pid, to receive the message:

    receive
        {From, Data} when is_pid(From) ->
            handle_data(From, Data)
    end

And beyond that, the process identified by Pid can be running on a physically separate host system - it's transparent.

Too bad we can't use Erlang for systems programming, but you can't have everything!