Using let in Scheme

I remember a post a while back where the author said that it's better to avoid using binding constructs like let in languages like Scheme. I was wondering how you'd rewrite something like this:
(let ((s (find (lambda (a) (char=? x (first a))) *translation-list*)))
 (if s (second s) x))

I think I'm loebing. Am I doing it right?


(define fix-helper (lambda (self f)
  (lambda args
    (apply f (cons (self self f) args)))))

(define fix (lambda (f) (fix-helper fix-helper f)))

(define rev (fix (lambda (f lis acc)
  (if (null? lis)
    acc
    (f (cdr lis) (cons (car lis) acc))))))

(define rev-map1 (fix (lambda (f fn lis acc)
  (if (null? lis)
    acc
    (f fn (cdr lis) (cons (fn (car lis)) acc))))))

(define map1 (lambda (fn lis)
  (rev (rev-map1 fn lis '()) '())))

(define loeb (fix (lambda (f fns)
  (map1 (lambda (fn)
          (lambda args
            (apply fn (cons (f fns) args))))
        fns))))

(define is-even_ (lambda (fs n)
  (apply (lambda (is-even is-odd)
           (if (= n 0)
             #t
             (is-odd (- n 1))))
         fs)))

(define is-odd_ (lambda (fs n)
  (apply (lambda (is-even is-odd)
           (if (= n 0)
             #f
             (is-even (- n 1))))
         fs)))

(define functions (loeb (list is-even_ is-odd_)))

(define is-even (car functions))
(define is-odd (cadr functions))