Close connection at halt (any change of at_halt/1 Vitor ?!!).

Investigate why plot_cpu/1 needs so much stack. (does it stilL ?)
Investigate the x.y notation and see if SWI can cope with it.
Calling functions natively ? 

We could drop the <- operator even, just hook an exception 
   handler for predicates that are not there !!!

--- threads (SWI, specific ?)
The R OS lib is thread-unsafe, add a Prolog layer to cope with this ?

Jan on Mailing list : 2013/1/10,

worker thread.  Just create a thread named 'R' and initialize R.

If you want to do something with R, use

    thread_self(Me),
    thread_send_message('R', process(Me, <data>)),
    thread_get_message(r_reply(Result))

and in the R thread, in a loop:

    thread_get_message(process(Sender, Data)),
    r_compute(Data, Result),
    thread_send_message(Sender, r_reply(Result)).

Of course, you need to make all this a bit cleaner and handle errors,
etc, but this is the basic idea.

--- r_session compatibility add-on ? 
one that would also solve the threading issue ?