RE: [External] : Re: Which Elisp types are mutable?

[Drew Adams]

> > Lisp symbols are a kind of object.  They have
> > attributes, including name, value (as a variable),
> > function definition, and an unlimited slew of
> > other attributes: their `symbol-properties'.
> 
> A symbol does not contain its properties. They're
> stored in some alist externally.

You're missing the point, it seems.  The distinction
is conceptual, not implementation.  Contain / have /
point to ... distinctions don't matter here.  And
their possible implementations matter even less.

By your criterion a cons cell doesn't contain its
cdr either - or its car.  A symbol is a thing that
has properties / attributes, whatever you want to
call them.  How it has them / where they're stored
is a completely different matter (and irrelevant here).

"Parts" of both a cons and a symbol are changeable.
They're both mutable, and that's the case using just
Lisp.  ("Parts", not "the parts".  Not all parts of
a symbol are changeable - e.g., the name isn't.)