Re: Appending lists

[Jean Louis]

* tomas@tuxteam.de <tomas@tuxteam.de> [2021-06-16 14:54]:
> On Wed, Jun 16, 2021 at 02:30:51PM +0300, Jean Louis wrote:
> 
> [...]
> 
> > (setq list '(A B C)) ⇒ (A B C)
> > (nconc list '(1 2 3)) ⇒ (A B C 1 2 3)
> > list  ⇒ (A B C 1 2 3)
> > 
> > So maybe he was thinking that symbol `list' does not change, and I
> > understood it that variable value does not change.
> > 
> > Why not come back to that and explain me how the variable `list' did
> > not change from (A B C) to (A B C 1 2 3)?
> 
> Because the content of 'list' (wasn't it 'list1' last time we talked?)
> is *not* the whole list. It is a reference to the list's head.
> 
> What changed was the cdr of some cons cell downstream. The variable
> doesn't see it.

You speak of some hidden flows? 

How is that useful for programer in Emacs Lisp?

Did variable's value change or not?

-- 
Jean

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