(defmacro sum (lst)
  `(reduce #'+ ,lst))

(defun proper-divisors (n)
  (when (> n 1)  
    (let ((divisors '())
          (limit (floor (sqrt n))))  
      (loop :for i :from 1 :to limit
            :when (zerop (mod n i))  
              :do (progn
                    (push i divisors)  
                    (when (/= n (floor n i))  
                      (push (floor n i)
                            divisors))))  
      (remove-duplicates (sort divisors #'<)
                         :test
                         #'equal))))

(defmacro sum-proper-divisors (n)
  `(sum (proper-divisors ,n)))

(defmacro is-abundant (n)  
  `(> (sum-proper-divisors ,n) ,n))

(defmacro gen-list (min max)
  `(loop :for n :from ,min :to ,max
         :collect n))

(defmacro filter (predicate list)
  `(remove-if-not ,predicate ,list))

(defmacro macro-to-function (macro-name)
  `(lambda (xs) (,macro-name xs)))

(defmacro db (x)
  `(* 2 ,x))

((lambda (xs) (db xs)) 2.1)

(funcall (macro-to-function db) 2.1)

;; Evaluation Context:

;; ((macro-to-function db) 2.1): This line attempts to call the result of the macro macro-to-function directly as if it were a function. However, since macro-to-function returns a lambda expression, this results in an "illegal function call" error because the macro is not expanded in the context of a function call.

;; (funcall (macro-to-function db) 2.1): In this line, funcall is used to invoke the lambda function returned by macro-to-function. This correctly evaluates the lambda and applies it to 2.1, allowing the macro to be expanded properly.

(defmacro abundant-numbers (limit)
  `(filter (macro-to-function is-abundant) (gen-list 1 ,limit)))

— Me@2024-09-20 11:53:30 PM

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2024.09.21 Saturday (c) All rights reserved by ACHK