gistfile1.rkt

(define (hyperize f id-e)
  (define (f* b n)
    (if (zero? n) id-e (f b (f* b (sub1 n)))))
  f*)

;; modified Knuth Up-Arrow notation
(define (↑ n)
  (cond ((zero? n) +)
        ((= n 1) (hyperize + 0))
        (else (hyperize (↑ (sub1 n)) 1))))

-> ((↑ 0) 4 5)
9
-> ((↑ 0) 4 10)
14
-> ((↑ 0) 2 3)
5
-> ((↑ 1) 2 3)
6
-> ((↑ 2) 2 3)
8
-> ((↑ 3) 2 3)
16
-> ((↑ 4) 2 3)
65536
-> ((↑ 5) 2 3)