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- To: dlw at MIT-AI
- Subject: DISPLACE
- From: JONL at MIT-MC (Jon L White)
- Date: Fri, 21 Mar 80 00:44:00 GMT
- Cc: (BUG LISP) at MIT-MC, NIL at MIT-MC
- Original-date: 20 MAR 1980 1944-EST
Date: 20 March 1980 16:42-EST
From: Daniel L. Weinreb <DLW at MIT-AI>
The Lisp documentation in LISP NEWS is typically done without much
thought; . . . MACLISP does not need lots of
little functions like (LAMBDA (X Y) (RPLACA X Y) (RPLACD X Y) X)
. . . . . . LISP NEWS
was not handed down on engraved tablets--we should reason together
about what the right thing is and what should be done about it.
Not to be picky about your conceptions of LISP NEWS, but this happens to
be the entry in LISP NEWS for DISPLACE, dated
"Sunday Sept 17,1978 FM+11H.57M.58S. LISP 1742 -HIC, JONL-"
" DISPLACE now treats atomic arguments differently.
Its definition is now like:
(DEFUN DISPLACE (X Y)
(AND (ATOM X) (ERROR '|-- not a list. (DISPLACE)| X))
(COND ((ATOM Y)
(RPLACA X 'PROGN)
(RPLACD X (NCONS Y)))
(T (RPLACA X (CAR Y))
(RPLACD X (CDR Y)))))"
By the bye, what prompted your comment?