School Commit Init

Anul 2/Semestrul 1/Programare logica si functionala/l3.lisp

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+; 12. Write a function that substitutes an element through another one at all levels of a given list.
+
+
+; substitute-element (old new lst):
+;   new if lst is atom and equal to old
+;   lst if lst is atom and not equal to old
+;   (substitute-element old new x) for each x in lst otherwise
+
+(defun substitute-element (old new lst)
+  (cond ((and (atom lst) (equal lst old)) new)
+        ((atom lst) lst)
+        (t (mapcar #'(lambda (x) (substitute-element old new x)) lst))))
+
+
+(print (substitute-element 'a 'z '(a (b a) (c (d a e)))))
+(exit)