Ari Johnson <firstname.lastname@example.org> wrote:
| Kamen TOMOV <email@example.com> writes:
| > Zach Beane wrote:
| >> What (first-class) object does POP modify?
| > [POP] modifies the place. As a consequence the place is modified.
| > As the place is an existing object we can conclude that POP modifies
| > an existing object.
| Are places first-class objects?
No, not in Common Lisp. However, some Lisps in the past [e.g., Lisp
Machines] have had first-class objects called "locatives" (locations),
which *denote* places, and could be dereferenced to get or set the
(LOCF <place>) ==> <location>
(LOCATION-REF <location>) ==> <value-of-place>
(SETF (LOCATION-REF <location>) <new-value>)
There was some discussion of them here in April 1999 which a search
of Google Groups might turn up. <news:firstname.lastname@example.org>
was one of the articles, which might help the search.
Rob Warnock <email@example.com>
627 26th Avenue <URL:http://rpw3.org/>
San Mateo, CA 94403 (650)572-2607