cloning elements in a list

[Robert L.]

Coby Beck wrote:

> > How to write a lisp function which clones the top-level elements of a list
> > (first arguement) n ( second argument) times. for eg. (clone 'A B C) 4 )
> > produces ( AAAABBBBCCCC)
>
> To rewrite your question to what I *think* you mean:
> (clone '(A B C) 4 )
> => (A A A A B B B B C C C C)
>
> try this:
> CL-USER 143 > (defun stretch (list factor)
> (loop for elt in list
> nconc (make-list factor :initial-element elt)))
> STRETCH
>
> CL-USER 144 > (stretch '(a b c) 4)
> (A A A A B B B B C C C C)

(require srfi/42) ; list-ec

(define (stretch the-list n)
(list-ec (:list x the-list) (:range _ n) x))

(stretch '(a b c) 4)
===>
'(a a a a b b b b c c c c)

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