;; comparing with racket:

   (define (grade student)
     (cond 
      [(excellent-work student) "A+"]
      [(and (okay-stuff student) (tried-hard student)) "B"]
      [(okay-stuff student) "B-"]
      [else "C"]))

   ;; Or

   (require racket/match)

   (define (grade student)
     (match (map (lambda (fn) (fn student)) 
                 '(excellent-work okay-stuff tried-hard))
       [(list #t _ _)  "A+"]
       [(list _ #t #t) "B"]
       [(list _ #t _)  "B-"]
       [else           "C"]))