The Tracer tool is a debugging aid which gives you an interface to the LispWorks
trace facilities. These allow you to follow the execution of particular functions and help you identify where errors occur during execution.
To create a Tracer, choose Window > Tools > Tracer or click in the LispWorks toolbar. Alternatively, a tracer can be created or displayed from within many other tools by choosing the command Trace > Show in Tracer in any menu whose commands operate on a traceable symbol.
The Tracer has three views:
LispWorks IDE User Guide (Macintosh version) - 13 Sep 2017