9 The Tracer
:step
option, but is also available via the Common Lisp form
(step form)where form is a form to be stepped and evaluated. It allows you to single-step through the evaluation of the form, stopping at each call.
You can include a call to step inside a tricky definition to invoke the stepper every time the definition is used.
There are a number of optional settings controlled by the keywords listed below. Use :help
within the stepper to see a list of the commands available at that time.
:s [n] Stepper command
Step this form, and all of its subforms. The optional argument n must be a positive integer. If supplied, :s
is executed n times.
:st Stepper command
Step this form without stepping its subforms.
:su Stepper command
Step up out of this form without stepping its subforms.
:sr Stepper command
Return a value to use for this form.
:sq Stepper command
Quit the current stepper level.
:redo Stepper command
Redo an event in the history list. This is the same as the normal listener :redo
command. See Chapter 10, "The Listener", for details.
:get Stepper command
Bind an event from the history list to a variable. This is the same as the normal listener :get
command. See Chapter 10, "The Listener", for details.
:help Stepper command
Prints the list of stepper commands available at that time.
:use Stepper command
Replace some element of a form (either a subform or symbol) by another event from the history list, then evaluate it. This is the same as the normal listener :use
command. See Chapter 10, "The Listener", for details.
:his Stepper command
Show a list of the last twenty events. This is the same as the normal listener :his
command. See Chapter 10, "The Listener", for details.
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