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From: "B. Pym" <Nobody447095@here-nor-there.org>
Newsgroups: comp.lang.lisp,comp.lang.scheme
Subject: Re: what's the best way to do this?
Date: Wed, 9 Jul 2025 05:29:47 -0000 (UTC)
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Pascal Bourguignon wrote:

> > >   (format t "~{~S~^:~}" list)
> 
> > I suspect this is the best LOOP that can be constructed:
> >
> > (loop for item in list
> >       for first = t then nil
> >       if first do (format t "~S" item)
> >       else do (format t ":~S" item))
> 
> If you don't want to use the simple format, you should rather avoid it
> in the loop.
> 
> (when list
>   (loop initially (princ (car list))
>         for item in (cdr list)
>         do (princ ":") (princ item) ))

Gauche Scheme

(define seq '(a b c d))

(when (pair? seq)
  (display (pop! seq))
  (for-each (cut  format #t ":~a" <>) seq))

  ===>
a:b:c:d