(define find-best
  (lambda (better lst)
    ; If the list has only one element
    (if (null? lst)
        (error "Cannot find the best value in an empty list")
        (if (null? (cdr lst))
            ; That's the best
            (car lst)
            ; Otherwise, use the better of the first element and the
            ; best remaining element.
            (better (car lst) (find-best better (cdr lst)))))))


(define better-value
  (lambda (compare? val1 val2)
    (if (compare? val1 val2) val1 val2)))

(define longest-string
  (lambda (lst)
    (find-best (lambda (str1 str2)
                   (better-value (lambda (str1 str2) 
                                   (> (string-length str1) (string-length str2)))
                                 str1 str2)) 
               lst)))

(define constant-5
  (lambda (x)
    5))

(define constant-6
  (lambda (x)
    6))

(define constant
  (lambda (n)    ; Given a number
    (lambda (x)  ; Return a procedure
      n)))       ; That returns the number

(define compare-to-choose
  (lambda (comparator?)
    (lambda (x y)
      (if (comparator? x y)
          x
          y))))