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setf order of evaluation
- To: email@example.com
- Subject: setf order of evaluation
- From: Timothy Daly <DALY@ibm.com>
- Date: Wed, 09 Sep 1987 14:31:00 -0000
(setq r '(a 1 b 2 c 3))
(setq s r)
(setf (getf r 'b) (progn (setq r nil) 6))
what is the value of R and S?
Note that P97 of CLtL states that SETF guarantees the
left-to-right order of evaluation of its arguments.
(yes, i know it is crufty to change R).
Both Symbolics and Lucid seem to generate
R = (B 8) and S = (A 1 B 2 C 3)
which implies that the second argument of setf
is evaluated first. What did I miss?
IBM T.J. Watson Research Center
Yorktown Heights, N.Y. 10598