Crawler Tractor.

; This is so good that maybe I shouldn't write about it, but leave ; programmers to recognize this strange specie, function non-recursive, ; and without loop yet evaluating indefintely. However, some readers ; of this blog do not use Newlisp, so here is how it works: ; ; The function initially contains only one expression - starting ; with begin. That expression (i) prints some message; (ii) inserts ; its COPY after currently evaluated expression to body of the ; function, and (iii) deletes previously evaluated expression from ; the body of the function. (set 'f (lambda()             (begin (println "Hi for the " (inc counter) ". time. ")                    (push (last f) f -1)                    (if (> (length f) 3) (pop f 1))))) (f) ; Hi for the 1. time. ; Hi for the 2. time. ; Hi for the 3. time. ; Hi for the 4. time. ; Hi for the 5. time. ; Hi for the 6. time. ; Hi for the 7. time. ; Hi for the 8. time. ; Hi for the 9. time. ; Hi for the 10. time. ; Hi for the 11. time. ; Hi for the 12. time. ; Hi for the 13. time. ; Hi for the 14. time. ; Hi for the 15. time. ; Hi for the 16. time. ; Hi for the 17. time. ; Hi for the 18. time. ; Hi for the 19. time. ; Hi for the 20. time. ; Hi for the 21. time. ;