10rec, Common Lisp

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;gnu clisp  2.49.60
#|
Для каждого блюда известен набор продуктов, необходимый для его приготовления, и количество каждого продукта. 
Дан список продуктов, имеющихся в наличии: какой продукт и сколько.
Написать функцию, формирующую возможное меню. Учитывать, что суммарное количество продуктов в меню не может превышать имеющееся.
|#

(defun ingredient-is-available (avails req)
    (cond 
        ((null avails) nil)
        ((string= (first (first avails)) (first req))
                 (cond
                     ((>= (second (first avails)) (second req)) t)
                     (t nil)
                     )
         )
        (t (ingredient-is-available (rest avails) req))
        
        )
  )

(defun ingredients-are-available (avails needed)
       (cond
           ((null needed) t)
           ((not (ingredient-is-available avails (first needed))) nil)
           (t (ingredients-are-available avails (rest needed)))
       )
    )

(defun reserve (avails ingr)
    (cond
        ((string= (first (first avails)) (first ingr)) (cons (list (first ingr) (- (second (first avails)) (second ingr))) (rest avails)))
        (t (cons (first avails) (reserve (rest avails) ingr)))
        )
    )

(defun reserve-ingredients (avails reqs)
    (cond
     ((null reqs) nil)
     (t 
          (progn
              (reserve avails (first reqs))
              (reserve-ingredients avails (rest reqs))
              ))
     )
    #|(loop for r in required-ingredients
          do (loop for a in available-ingredients
               if (string= (first a) (first r))
                do (setf (second a) (- (second a) (second r))) and
                return nil
           )
     )
    available-ingredients
    |#
    )

(defun make-menu (available-ingredients dishes) 
    (let (menu))
    (setf menu (list))
    (loop for d in dishes
         if (ingredients-are-available available-ingredients (second d))
          do (setf available-ingredients (reserve-ingredients available-ingredients (second d))) and
          do (setf menu (nconc menu (list d)))
     )
    menu
    )

(let (available-ingredients))
(setf available-ingredients '(("carrot" 2000) ("onion" 1300) ("potato" 5000) ("chicken" 800) ("zuccini" 500) ("sausage" 600) ("cheese" 500)))

(let (dishes))
(setf dishes '(("roasted potato" (("potato" 1300) ("onion" 400))) ("zuccini slice" (("zuccini" 400) ("cheese" 500) ("onion" 300) )) 
                                                                  ("baked potato" (("potato" 2000) ("sausage" 500) ("cheese" 400)))  ))

(print "Продукты в наличии: ")
(print available-ingredients)
(print "____________________________________")
(print "Блюда: ")
(print dishes)
(print "____________________________________")
(print "Меню: ")
(print ( make-menu  available-ingredients dishes))

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