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[FORTRAN] will persist for some time -- probably for at least the next decade. -- T. Cheatham

devel / comp.lang.lisp / .re: Please help

.re: Please help

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https://www.rocksolidbbs.com/devel/article-flat.php?id=16950&group=comp.lang.lisp#16950

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From: No_spamming@noWhere_7073.org (Robert L.)
Newsgroups: comp.lang.lisp
Subject: .re: Please help
Date: Mon, 7 Mar 2022 09:27:35 -0000 (UTC)
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by: Robert L. - Mon, 7 Mar 2022 09:27 UTC

"Private Oracle" wrote:

> I'm new to LISP and I've got a real bugger of
> a problem here : I need to define a function
> which duplicates every occurance of a given
> element in a given list. Suppose this funtion
> was called DUPLIC8, then the call
>
> (DUPLIC8 '(A B C D E B) 'B))
>
> should produce (A B B C D E B B).

Gauche Scheme or Racket:

(define (duplic8 items which)
(append-map
(lambda (x)
(if (equal? x which)
(list x x)
(list x)))
items))

(duplic8 '(a b c b) 'b)
===>
(a b b c b b)