While I'm whining...
If, in the *slime-repl*, you do
XOS> (setf *print-base* 16)
the next time to you C-c C-c to compile a completely innocuous and correct function, you end up with this:
;;; Compiling file /tmp/filebPzYl6.lisp ... ;;; Safety = 3, Speed = 1, Space = 1, Float = 1, Interruptible = 0 ;;; Compilation speed = 1, Debug = 2, Fixnum safety = 3 ;;; Source level debugging is on ;;; Source file recording is on ;;; Cross referencing is on
**++++ Error between functions: The variable |1501E| is unbound. ; *** 1 error detected, no fasl file produced.
Cheers, --ap