Upon leaving a function that is being traced,
*traced-results* is bound to the list of results from the function.
*traced-results* is then printed after the function name in the output from tracing. It is accessible in the
:after forms to trace. However care should be used when manipulating this variable, since it is the value of
*traced-results* itself that is used when returning from the traced function. Thus if this value is altered by the
:after forms then the caller of the traced function receives the altered results.
LispWorks User Guide and Reference Manual - 13 Feb 2015