R.pl hangs in debian linux

So I've been trying the R package from Swipl Git, but the example  
given in the package just hangs.

:- ensure_loaded(library('R')).

rtest :-
         r_open,
         y <- rnorm(50),
         r_print( y ),
         x <- rnorm(y),
         r_in( x11(width=5,height=3.5) ),
         r_in( plot(x,y) ),
         write( "Press Return to continue..." ), nl,
         read_line_to_codes( user_input, _ ),
         r_print( "dev.off()" ),
         Y <- y,
         write( y(Y) ), nl,
         findall( Zx, between(1,9,Zx), Z ),
         z <- Z,
         r_print( z ),
         cars <- c(1, 3, 6, 4, 9),
         r_in(pie(cars)),
         write( "Press Return to continue..." ), nl,
         read_line_to_codes( user_input, _ ),
         r_close.

I tried single quotes in the above code but it would not compiled correctly.

[rexample].
%    library(pairs) compiled into pairs 0.00 sec, 22 clauses
%   library(lists) compiled into lists 0.01 sec, 122 clauses
%    library(shlib) compiled into shlib 0.00 sec, 39 clauses
%    library(option) compiled into swi_option 0.00 sec, 32 clauses
%   library(readutil) compiled into read_util 0.01 sec, 114 clauses
%   library(process) compiled into process 0.00 sec, 38 clauses
%  library(R) compiled into r_session 0.04 sec, 486 clauses
% rexample compiled 0.04 sec, 491 clauses
true.

Then I called rtest. and it just hangs. I check if the x11 window  
opened, which it did not. I get the following when I list the process:

4516 pts/1    00:00:28 evince
  4520 pts/1    00:00:00 dbus-launch
  4785 pts/1    00:00:00 sudo
  4787 pts/1    00:00:00 su
  4795 pts/1    00:00:00 bash
  5182 pts/1    00:00:00 swipl
  5183 pts/1    00:00:00 R
  5185 pts/1    00:00:00 R <defunct>
  5230 pts/1    00:00:00 swipl
  5231 pts/1    00:00:00 R
  5233 pts/1    00:00:00 R <defunct>
  5243 pts/1    00:00:00 swipl
  5244 pts/1    00:00:00 R
  5246 pts/1    00:00:00 R <defunct>
  5256 pts/1    00:00:00 ps

I tried the R code in an interactive R session and it worked.

My SWI-Prolog version is as follows:
Welcome to SWI-Prolog (Multi-threaded, 64 bits, Version 6.5.2)

My R version is as follows:
R version 3.0.1 (2013-05-16) -- "Good Sport"
Platform: x86_64-unknown-linux-gnu (64-bit)

And finally, I'm running the following linux version:
Linux version 3.2.0-4-amd64 ([email protected])
(gcc version 4.6.3 (Debian 4.6.3-14))

I've only read that there was issues with OSX from mac regarding x11.  
Still I tried the r_open(with(non-interactive)) option and I still get  
the same result.

Best Regards,


Bob Ly