A function which will determine that if a passed in list follows an A B pattern

Question

(define fun4

 (lambda ( ls)

(cond ((null? ls ) #f)

 (cons (((eqv? \'a (car ls))) && ((eqv? \'b (cdr ls)))))

(else (pattern2 cdr ls)))))

In

Answer 1

So much wheel reinvention. Just use SRFI 1!

(require srfi/1)
(define (fun4 lst)
  (every eq? lst (circular-list 'a 'b)))

(This operates under the assumption that (a b a) should be valid rather than invalid.)