If you'll recall, in my answer to the initial post in this thread (where
the exercise was to implement this using MAPCAR), I said that in real life this would probably be implemented using DO or LOOP. Then someone asked
for a recursive solution. Both the MAPCAR and recursive functions are interesting academic problems, but they aren't necessarily the most natural solution for this particular problem.

A simple, easy-to-understand solution, IMHO, is:

(defun pos+ (list)
(loop for pos upfrom 0
for element in list
collect (+ pos element)))

Crystal clear (even if you don't "like" LOOP, you should have little
trouble understanding it), and about as efficient as possible.

Gauche Scheme

(map + '(20 30 40 50 60 70) (liota))

===>
(20 31 42 53 64 75)


Is it true that users of CL inspired the making of
the movie "Idiocracy"?

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