Success: [eclipse]: [user]. w(X) :- writeln(X). user compiled 44 bytes in 0.00 seconds yes. [eclipse]: trace. yes. Debugger switched on - creep mode [eclipse]: w(X = 2). (1) 0 CALL w(_g54 = 2) (dbg)?- creep % type c B (2) 1 CALL writeln(_g54 = 2) (dbg)?- creep _g54 = 2 B (2) 1 EXIT writeln(_g54 = 2) (dbg)?- creep (1) 0 EXIT w(_g54 = 2) (dbg)?- creep X = _g54 yes. [eclipse]: nodebug. Debugger switched off yes. [eclipse]: w(X = 2). _g54 = 2 X = _g54 yes.