title: maplist error?
body: <p>The following used maplist works in swi-prolog not in gprolog:</p>
  
  <pre><code>GNU Prolog 1.3.1
  By Daniel Diaz
  Copyright (C) 1999-2009 Daniel Diaz
  | ?- maplist(writeln,[1,2,3]).
  uncaught exception: error(existence_error(procedure,maplist/2),top_level/0)
  | ?-
  </code></pre>
  
  <p>Regards!</p>