3.2 Simple use of the REPL debugger

Upon entering the debugger as a result of an error, a message describing the error is printed and a number of options to continue (called restarts) are presented. Thus:

CL-USER 6 > (/ 3 0)
 
Error: Division-by-zero caused by / of (3 0)
  1 (continue) Return a value to use
  2 Supply new arguments to use
  3 (abort) return to level 0.
  4 return to top loop level 0.
  5 Destroy process.
 
Type :c followed by a number to proceed
 
CL-USER 7 : 1 > 

To select one of these restarts, enter :c (continue) followed by the number of the restart. So in the above example you could continue as follows:

CL-USER 7 : 1 > :c 2
 
Supply first number: 33
 
Supply second number: 11
3
 
CL-USER 8 > 

There are two special restarts, a continue restart and an abort restart. These are indicated by the bracketed word continue or abort at their start. The continue restart can be invoked by typing :c alone. Similarly, the abort restart can be invoked by entering :a. So an alternative continuation of the division example would be:

CL-USER 7 : 1 > :c
 
Supply a form to be evaluated and used: (+ 4 5)
9