Transform recursion into tail recursion

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Remove a white dot from the photo | Euler problem 24.1.2

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(defmacro detailn (fn (n)
                   (if endc
                       b-val
                       (op n (fn (ch n)))))
  (let ((acc (gensym)))
    `(defun ,fn (,n)
       (labels ((fn-iter (,n ,acc)
                  (if ,endc
                      ,acc
                      (fn-iter (,ch ,n)
                               (,op ,n ,acc)))))
         (fn-iter ,n ,b-val)))))

(detailn facn (m)
         (if (<= m 1)
             1
             (* m (facn (1- m)))))

(macroexpand '(detailn fac (m)
               (if (<= m 1)
                   1
                   (* m (fac (1- m))))))

— Fixed by GIMP’s Clone Tool

— Me@2024-10-30 12:42:22 PM

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2024.11.06 Wednesday (c) All rights reserved by ACHK