Lisp

[Saleh Fakka]

Hi

I'm trying to test the find-path function by calling it,

(defparameter *graph* '((A B C)                        (B A C D)                        (C A B D)                        (D B C))) (defun find-path (start end)  (if (equal start end)      (list start)      (loop for node in (cadr (assoc start *graph*))            when (find-path node end)     return (cons start it)))) (find-path 'A 'D)

I'm getting this error

Error: Illegal argument to endp: A
[condition type: TYPE-ERROR]

[Tim Holloway]

Welcome to the Ranch, Saleh!

Unfortunately, LISP isn't very standardized, so it would help if you'd tell us what dialect of LISP your are running on and what platform. I have Common Lisp (clisp) for Linux, Guile (Scheme) and eLisp (Emacs internal LISP) just that I know of. Oh yes, and whatever my Festival speech synthesizer uses!

I tried your sample code out on clisp, and I got this:

-----------------------------------------------------------------------------

[1]> (defparameter *graph* '((A B C)
                      (B A C D)
                      (C A B D)
                      (D B C)))

(defun find-path (start end)
 (if (equal start end)
    (list start)
    (loop for node in (cadr (assoc start *graph*))
          when (find-path node end)
   return (cons start it))))

(find-path 'A 'D)
*GRAPH*
[2]>
FIND-PATH
[3]>
*** - ENDP: A proper list must not end with B
The following restarts are available:
ABORT          :R1      Abort main loop

----------------------------------------------------------

I haven't tried to dissect this stuff in detail, but my suspicion is that probably you aren't quoting everything you need to quote.

[Saleh Fakka]

Thank you

Im using ACL