Re: Given string 'a.bc.' -- replace each dot(.) with 0 or 1

Kaz Kylheku <643-408-1753@kylheku.com> writes:

On 2024-05-18, HenHanna <HenHanna@devnull.tb> wrote:

< >
< > 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')
< >
< > -- The order is not important.
< >              If the string has 3 dots, the value is a list of length 8.
< >
< > If the program is going to be simpler,
< >                        pls use, e.g.   (a $ b c $)  rather than  'a.bc.'

>
TXR Lisp:
>
(defun bindots (str)
  (let* ((s (copy str))
         (ixs (where (op eql #\.) s))
         (n (len ixs)))
    (collect-each ((digs (rperm '(#\0 #\1) n)))
      (set [s ixs] digs)
      (copy s))))

where is collect-each in common lisp?
 set [x] is no good! not in lisp