[no subject]

[KMP at MIT-MC (Kent M. Pitman)]

If you get time, can you look at this:

(LOAD '((DSK TURNIP) XHOOK FASL))
(MAR-TRACE 'A) ; Note that this MAR-TRACE, tho' implemented as a Macro, takes
	       ;  its args in SUBR (evaluable) fashion....
(SETQ A 3)
;A set to 3 
;** Break? n [No]

(SETQ B '(A B C))
(MAR-TRACE B) ; Trace value of B
(RPLACA B 'FOO)
;(A B C) has been bashed 
;** Break? n [No]
;(A B C) has been bashed 
;** Break? n [No]
;(A B C) has been bashed 
;** Break? n [No]
... etc. 

[1] For SETQ's, the MAR interrupt seems to happen after the assignment. For
    RPLACA's it happens before. Both should happen before and some hook should
    be available for finding the old and new values.

[2] In any case, the RPLACA seems to get in an infinite loop no matter what
    and refuses to ever change its value ...

This is proving to be a useful debugging tool to JIM, WGD, and myself for
some obscure bugs in Macsyma, but we'd like it to work correctly. Can you
take a look at it? I can't make heads or tails of what's going on...
Thanks. -kmp