Stack overflow from recursive function call in Lisp

Question

I am learning Lisp from the book \"The Land of Lisp\" by Conrad Barski. Now I have hit my first stumbling block, where the author says:

Calling yourse

Answer 1

(DEFUN nrelem(l) 
    (if (null l)
        0
       (+ (nrelem (rest l)) 1)
))