🚀 go-pugleaf

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Hi,

It's probably not important at all.. :-)

in The Elisp Reference Manual

in node Lists -> Modifying Lists -> Setcdr

in second example, the picture is false, and we didn't simply "delete"
b from the list, we created a new cons for c and lost the old one (for GC :-)

Example:

(setq x1 '(a b c))      = (a b c)
(setq x2 (cdr x1))      = (b c)
(eq x2 (cdr x1))        = t
(setcdr x1 '(c))        = (c)
x1                      = (a c)
x2                      = (b c)
(cdr x1)                = (c)
(cdr x2)                = (c)
(eq (cdr x1) (cdr x2))  = nil

Here is the result in box notation:

                         
      ---------------         ---------------
     |car    |cdr    |       |car    |cdr    |
     |   a   |   o---------->|   c   |  nil  |
     |       |       |       |       |       |
      ---------------         ---------------

      ---------------         ---------------
     |car    |cdr    |       |car    |cdr    |
     |   b   |   o---------->|   c   |  nil  |
     |       |       |       |       |       |
      ---------------         ---------------


Cheers,
Christophe.

 -=- Computers are useless; they can only give answers.  -- Picasso   -=-