A final interface mechanism is
with-prolog. with-prolog
allows one to embed prolog into an arbitrary lisp function. Lisp variables are referenced in Prolog using "
?
.
<name>
".
(defun palindromep (x)
(with-prolog
(append ?a (?b . ?c) ?.x) ; note "?.x" reference
(or (reverse ?a ?c)
(reverse ?a (?b . ?c)))))
(palindromep '(yes no maybe))
NIL
(palindromep '(yes no maybe no yes))
T
The body of a
with-prolog
returns
t
if it succeeds and a non-local exit is not executed. It returns
nil
on failure.