Debugger Banner - SBCL 1.0.31 User Manual
Description: SBCL 1.0.31 User Manual

Next: Debugger Invocation, Up: Debugger Entry

#### 5.1.1 Debugger Banner

When you enter the debugger, it looks something like this:

         debugger invoked on a TYPE-ERROR in thread 11184:
           The value 3 is not of type LIST.

         You can type HELP for debugger help, or (SB-EXT:QUIT) to exit from SBCL.

         restarts (invokable by number or by possibly-abbreviated name):
           0: [ABORT   ] Reduce debugger level (leaving debugger, returning to toplevel).
           1: [TOPLEVEL] Restart at toplevel READ/EVAL/PRINT loop.
         (CAR 1 3)
         0]

The first group of lines describe what the error was that put us in the debugger. In this case `car` was called on `3`, causing a `type-error`.

This is followed by the “beginner help line”, which appears only if `sb-ext:*debugger-beginner-help*` is true (default).

Next comes a listing of the active restart names, along with their descriptions – the ways we can restart execution after this error. In this case, both options return to top-level. Restarts can be selected by entering the corresponding number or name.

The current frame appears right underneath the restarts, immediately followed by the debugger prompt.