tanky:~/src/toys% sh dump-differs-from-compile.sh
===== Load then dump =====
This is SBCL 1.0.48.19, 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.
[undoing binding stack and other enclosing state... done]
[saving current Lisp image into foo.core:
writing 3512 bytes from the read-only space at 0x01000000
writing 2256 bytes from the static space at 0x01100000
writing 32034816 bytes from the dynamic space at 0x09000000
done]
===== Load then compile =====
This is SBCL 1.0.48.19, 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.

; compiling file "/home/james/src/toys/foo.lisp" (written 11 DEC 2011 02:04:24 PM):
; compiling (IN-PACKAGE #:CL-USER)
; compiling (DEFSTRUCT FOO ...)
; compiling (DEFUN MAIN ...)
; file: /home/james/src/toys/foo.lisp
; in: DEFUN MAIN
;     (LET ((MY-FOO #S(FOO :BAR 'BAR-VAL :BAZ 'BAZ-VAL)))
;       MY-FOO)
; ==>
;   #S(FOO :BAR 'BAR-VAL :BAZ 'BAZ-VAL)
; 
; caught ERROR:
;   don't know how to dump #S(FOO :BAR 'BAR-VAL :BAZ 'BAZ-VAL) (default MAKE-LOAD-FORM method called).
; 
; note: deleting unreachable code
; 
; note: deleting unreachable code
; 
; compilation unit finished
;   caught 1 ERROR condition
;   printed 2 notes


; /home/james/src/toys/foo.fasl written
; compilation finished in 0:00:00.011