Subject: Re: Lisp on TV Date: 11 Oct 1998 22:09:08 GMT From: Steve Gonedes
Newsgroups: comp.lang.lisp firstname.lastname@example.org (Barry Margolin) writes: < In last night's episode of "The Net" (on the USA cable network), which < will be rerun tonight at 11pm EDT, there's a scene where a hacker is < breaking into the computer system that runs the electric power grid. Set < your VCRs and freeze on the screen shot (it's about 15 minutes into the < episode). It looked to me like a couple of functions from a logic < programming language (perhaps a Prolog interpreter) in Lisp. Anyone < recognize where the code is from? Here's what I was able to see in the < screen shot: < < (lexpand 'bk-out hostile) < < (defconstant unbound "unbound") < < (defmacro deref (exp) < "Follow pointers for bound variables." < `(progn (loop while (and (var-p ,exp) (bound-p ,exp)) < do (setf ,exp (var-binding ,exp))) < ,exp)) < < (defstruct var name (binding unbound)) < < (defun bound-p (var) (not (eq (var-binding var) unbound) < < (defun unify (x y) < "Destructively unify two expressions" < (cond ((eql (deref x) (deref y) x) < ((var-p x) (set-binding1 x y)) < ((var-p y) (set-binding1 y x)) < ((and (bound-p x) (bound-p y)) < (and (unify (deref x) (deref y)) < With the exception of (lexpand 'bk-out), it looks like the stuff on page 377 and 378 of Norvig's Case Studies in CL, book.