22822 jsnell ldb (1:15) :/tmp> cat h.lisp (defun foo (x) (declare (optimize (debug 2))) (let ((n (1+ x))) (print n) (print (/ 1 x)) ldb (1:15) :/tmp> sb 0.9.14.8 --load h.lisp This is SBCL 0.9.14.8, an implementation of ANSI Common Lisp. More information about SBCL is available at <http://www.sbcl.org/>. SBCL is free software, provided as is, with absolutely no warranty. It is mostly in the public domain; some portions are provided under BSD-style licenses. See the CREDITS and COPYING files in the distribution for more information. (*(foo 0) 1 debugger invoked on a DIVISION-BY-ZERO in thread #<THREAD "initial thread" {10022AEA31}>: arithmetic error DIVISION-BY-ZERO signalled Operation was SB-KERNEL::DIVISION, operands (1 0). restarts (invokable by number or by possibly-abbreviated name): 0: [ABORT] Exit debugger, returning to top level. (SB-KERNEL::INTEGER-/-INTEGER 1 0) 0] down (FOO 0) 1] L N = 1 X = 0 1] (sb-debug:var 'N) 1 1] 3362249050 #lisp