Re: sharing list structure

[Thien-Thi Nguyen <ttn@glug.org>]

Joe Corneli <jcorneli@math.utexas.edu> writes:

> OK, I think I've got the idea now.  But still, I'm
> surprised that `setq' is not among the list of
> "destructive functions".  What's that about?

setq changes a symbol's value to a new value.

a symbol and its value are two different concepts.

the "destructiveness" of a function does not refer
to the binding between a symbol and its value, but
rather how the cdr of a pair is treated.

check out gnugo.el, which uses tail-pointer style
extensively.  also: reverse:nreverse::append:nconc
(more or less, pedants be damned).

thi