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NNTP-Posting-Date: Sun, 19 May 2024 06:06:15 +0000
From: steve <sgonedes1977@gmail.com>
Newsgroups: comp.lang.lisp
Subject: Re: Given string 'a.bc.' -- replace each dot(.) with 0 or 1
References: <v29p14$2mr5l$2@dont-email.me>
	<m3jzjqlbui.fsf@leonis4.robolove.meer.net>
Date: Sun, 19 May 2024 02:06:15 -0400
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Madhu <enometh@meer.net> writes:

> * HenHanna <v29p14$2mr5l$2@dont-email.me> :
> Wrote on Sat, 18 May 2024 01:31:32 -0700:
>
< > How can i write this function simply?   (in Common Lisp)
< >
< > -- Given a string  'a.bc.'   -- replace each dot(.)  with 0 or 1.
< >
< >        -- So the value is a list of 4 strings:
< >                                  ('a0bc0'  'a0bc1'  'a1bc0'  'a1bc1')
>
> (defun adjusted-logbitp (pos num total-width)
>   (let* ((int-len (integer-length num))
> 	 (i (- pos (- total-width int-len))))
>     (if (< i 0)
> 	nil
> 	(logbitp i num))))
>
> (defun bindots (str)
>   (let* ((indices (loop for c across str for i from 0
> 		       if (eql c #\.) collect i))
> 	(width (length indices)))
>     (loop for i below (expt 2 width)
> 	  collect (let ((ret (copy-seq str)))
> 		    (loop for j in indices
> 			  do (setf (aref ret j)
> 				   (if (adjusted-logbitp j i width)
> 				       #\1
> 				       #\0)))
> 		    ret))))

what about substitute? common lisp is not scheme of the week.