Question

Say I have a function that takes a list and does something:

(defun foo(aList)
   (loop for element in aList ...))

But if the list is nested I want to flatten it first before the loop does stuff, so I want to use another function (defun flatten(aList)) that flattens any list:

(defun foo(flatten(aList))
   (loop for element in aList ...))

Lisp doesn’t like this. Is there another direct way around this?

Answer 1

Here’s one way:

(defun foo (alist)
  (loop for element in (flatten alist) ...)