
trace(+Goal)

   Execute the goal Goal with the debugger in creep mode.



Arguments
   ?Goal               Atom or compound term.

Type
   Debugging

Description
   The goal Goal is called with the debugger in creep mode.
   trace/1 succeeds or fails depending if Goal succeeds or fails.


   This predicate is particulary useful for debugging large programs that
   would take too much space or time to run completely with the debugger.
   The debugger is only switched on in creep mode at the call port of Goal
   and switched off when Goal exits (or fails, leaves,...).


   If the debugger was already on before calling trace/1, it has
   no effect.


   An alternative way of turning on the debugger selectively is to
   set the start_tracing property of a particular predicate using
   set_flag/3.




Resatisfiable
      No.

Fail Conditions
      Fails if Goal fails.



Examples
   
Success:
      [eclipse]: [user].
       p :- big_goal1, trace(buggy_goal), big_goal2.
       big_goal1.
       big_goal2.
       buggy_goal.
       user        compiled 208 bytes in 0.02 seconds
      yes.
      [eclipse]: p.
        % big_goal1/0 is executed without the debugger
      Start debugging - creep mode
        (1) 0  CALL   buggy_goal %> creep
        (1) 0  EXIT   buggy_goal %> creep
      Stop debugging.
        % big_goal2/0 is executed without the debugger
      yes.





See Also
   notrace / 0, trace / 0, debug / 0, debug / 1, set_flag / 3
