Re: problems of everyday life

[Emanuel Berg]

Akib Azmain Turja wrote:

> Someone implemented addition using sleep.  Now I have implemented
> subtraction:
>
> (defun subtract (x y)
>   (when (< y x)
>     (let ((tmp x))
>       (setq x y)
>       (setq y tmp)))
>   (let ((time-a (current-time)))
>     (sleep-for x)
>     (let ((time-b (current-time)))
>       (while (< (float-time (time-subtract nil time-a)) y)
>         (sleep-for 0.9))
>       (floor (float-time (time-subtract nil time-b))))))
>
> (subtract 0 1)     ; => 1
> (subtract 3 5)     ; => 2

What about recursive counting?

(defun recursive-count (n)
  (if (zerop n)
      0
    (1+ (recursive-count (1- n))) ))

(recursive-count 5) ; 5

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