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From: "B. Pym" <Nobody447095@here-nor-there.org>
Newsgroups: comp.lang.lisp
Subject: Re: binary rep as list? string-to-list?
Date: Mon, 16 Jun 2025 12:30:03 -0000 (UTC)
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> > .. but now stuck on how to convert the "1001" string into a (1 0 0 1)
> > integer list. Any help appreciated --- thanks!
> 
> an iterative solution:
> 
> (loop for digit across (write-to-string 9 :base 2) collect
>       (if (char= digit #\1) 1 0))
> 
> or a more functional solution:
> 
> (map 'list
>      #'(lambda (x) (if (char= x #\1) 1 0))
>      (write-to-string 9 :base 2))

Scheme:

(map string->number (map string (string->list "1001")))
 ===>
(1 0 0 1)