(define count-reflexive-pairs
  (lambda (rel)
    (cond [(null? rel) 0]
	  [(equal? (caar rel) (cadar rel))
	   (+ 1 (count-reflexive-pairs (cdr rel)))]
	  [else (count-reflexive-pairs (cdr rel))])))

(define count-reflexive-pairs
  (lambda (rel)
    (if (null? rel)
	0
	(let ([cdr-rflx-ct (count-reflexive-pairs (cdr rel))])
	  (if (equal? (caar rel) (cadar rel))
	      (+ 1 cdr-rflx-ct)
	      cdr-rflx-ct)))))

(define count-reflexive-pairs
  (lambda (rel)
    (if (null? rel)
	0
	(+ (count-reflexive-pairs (cdr rel))
	   (if (equal? (caar rel) (cadar rel))
	       1
	       0)))))

(define count-reflexive-pairs
  (lambda (rel)
    (count-with-acc rel 0)))

(define count-with-acc
  (lambda (rel count)
    (if (null? rel)
	count
	(count-with-acc (cdr rel)
			(+ count
			   (if (equal? (caar rel) (cadar rel))
			       1
			       0))))))

(count-reflexive-pairs '()) ; 0
(count-reflexive-pairs '((a b) (b c) (a a) (b b) (c a))) ;2
(count-reflexive-pairs '((a a))) ; 1