11 Debugging Features

When debugging a program, programmers often find it helpful to examine the program's internal status while it runs: the values of internal variables, the choices made in if and cond statements, and so forth. Guile Scheme provides a debugging interface that programmers can use to single-step through Scheme functions and examine symbol bindings. This is different from the Debugging, which permits programmers to debug the Guile interpreter itself. Most programmers will be more interested in debugging their own Scheme programs than the interpreter which evaluates them.

The debugging features are normally automatically loaded upon invocation, but should you find the need, you can manually ensure their availability by evaluating the form:

     (use-modules (ice-9 debug))

[FIXME: should we include examples of traditional debuggers and explain why they can't be used to debug interpreted Scheme or Lisp?]

• Single-Step: Execute a program or function one step at a time.
• Trace: Print a report each time a given function is called.
• Backtrace: See a list of the statements that caused an error.
• Fancy Debugging: Featureful sub-repl.