anchor.diff:                     (evaluate-population population repeat-var args fargs))))
   
   (defun get-min-max (alist predicate key)
  -  (when list
  -    (let* ((m0 (first list))
  +  (when alist
  +    (let* ((m0 (first alist))
              (m1 (funcall key m0)))
         (mapc (lambda (e0 &aux (e1 (funcall key e0)))
                 (when (funcall predicate e1 m1)
                   (psetf m0 e0 m1 e1)))
  -            list)
  +            alist)
         m0)))
   
   (defun tournament-selection (fitness-alist program-count)
  -  (mapcar #'car (get-min-max (loop for r-count upto program-count collect
  -                                   (pick-random fitness-alist)) #'> #'second)))
  +  (car (get-min-max (loop for r-count upto (- program-count 1) collect
  +                          (pick-random fitness-alist)) #'> #'cdr)))
   
   (defun fair-coin (chance)
     (let ((toss (random 101)))
  
positive.code:              generation
               (generate-population primitives actions conditionals max-tree-depth member-count)))
           (population-fitness (generation-fitness population args fargs fitness-function repeat-var))
           (passes (remove-if-not #'(lambda (x) (fitness-p (cadr x))) population-fitness)))
      (if passes
        passes
        (evolve primitives actions conditionals args fargs fitness-function fitness-p
  
negative.code:       (quote tree))))
  
  (defun replace-subtree (tree nth-list replacement)
    (if nth-list
      (macrolet
        ((macro-nth (atree list-nth)
                    `(eval (list 'lambda '(tree replacement)
                                 (list 'setf (recursive-nth ,atree ,list-nth) 'replacement)))))
        (let ((setf-return (funcall (macro-nth tree nth-list) tree replacement)))
          tree))
      tree))
  
  (defun crossover (mother father)
    (let* ((father-st (pick-random-subtree father))
           (mother-st-acc (pick-random-subtree mother father))
           (mother-st (replace-subtree mother mother-st-acc father-st)))
      mother-st))
  
  (defun copy-population (fitness-alist &optional (percentage 10) (program-count 7))
  