freeman@argosy.UUCP (Jay R. Freeman) (09/26/90)
In regard to the construct `(,a b c), I thought the R3 standard
(haven't seen the later ones yet) indicates that all of what is
returned by backquote is immutable; that is, if we do
(define a 42)
(define foo `(,a b c))
making the value of foo be (42 b c), then the following are errors:
(set-car! foo 88)
(set-cdr! foo 88)
(set-car! (cdr foo) 88)
(set-cdr! (cdr foo) 88)
(set-car! (cddr foo) 88)
(set-cdr! (cddr foo) 88)
(This list doesn't go any further, because (cdddr foo) is the empty
list, which is not capable of being set-car!ed and set-cdr!ed anyway.)
If I am right, this is a somewhat stricter interpretation than in
Common Lisp. Do people agree or disagree?
-- Jay Freeman
<canonical disclaimer -- I speak only for myself>