4.2 Tracing options

4.2.3 Using the debugger when tracing

:break

Trace keyword

:break form

: If form evaluates to non-nil, the debugger is entered directly fromtrace. If it returnsnil, tracing continues as normal. This option lets you force entry to the debugger by supplying a form as simple ast.
: Upon entry to the traced function, the standard trace information is printed, any supplied:before forms are executed, and then form is evaluated.

:break-on-exit

Trace keyword

:break-on-exit form

: Like:break, this option allows you to enter the debugger fromtrace. It differs in that the debugger is entered after the function call is complete.
: Upon exit from the traced function, the standard trace information is printed, and then form is evaluated. Finally, any supplied:after forms are executed.

:backtrace

Trace keyword

:backtrace backtrace

Generates a backtrace on each call to the traced function. backtrace can be any of the following values: