towers of hanoi | Takeuchi function | combinations of a set | letrec macro
;;; LTAK (list-based TAK) benchmark
(let*
((six (quote (1 2 3 4 5 6)))
(twelve (append six six))
(eighteen (append six twelve)))
(labels
((ltak (x y z)
(cond ((not-longer x y) z)
(t (ltak (ltak (cdr x) y z)
(ltak (cdr y) z x)
(ltak (cdr z) x y)))))
(not-longer (a b)
(cond ((eq nil a))
((eq nil b) nil)
(t (not-longer (cdr a) (cdr b)))))
(ntimes (n)
(cond ((null n))
(t (print (ltak eighteen twelve six))
(ntimes (cdr n))))))
(ntimes '(1 2 3 4 5 6 7 8 9 10))))