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Re: master 9c82f480590: Move and edit text about lexical environment rep

From: Mattias Engdegård
Subject: Re: master 9c82f480590: Move and edit text about lexical environment representation
Date: Sun, 22 Oct 2023 10:03:46 +0200

22 okt. 2023 kl. 06.47 skrev Michael Heerdegen <michael_heerdegen@web.de>:

>> +Lisp debuggers.  Each member of the list is either a cons cell which
>> +represents a lexical symbol-value pair, or a symbol representing a
>> +dynamically bound variable.
> I have two questions/things that are unclear to me: First, the docstring
> of `eval' talks about LEXICAL as an "alist mapping" which seems not to
> be exact if it is allowed to contain plain symbols.  Should the
> docstring be clarified as well?

Probably, yes. Doc strings are often somewhat simplified but a little accuracy 
wouldn't cost us much here.

> Second: you wrote "or a symbol representing a dynamically bound
> variable".  Does this variable really have to be bound (to a value), or
> do you mean "dynamically binding" (aka special)?

The latter: it represents a (defvar SYMBOL) declaration at that point.
The parameter has exactly the same type as internal-interpreter-environment 
which is described in a comment in eval.c.

>  And such a member VAR
> in LEXICAL means that the VAR is special when FORM is evaluated - even
> when the variable has not been declared special in the outer
> context...or something else?

No, you are right. Example:

(defun pz () (defvar z) z)

(eval '(let ((z 3)) z) t)  => 3
(eval 'z '((z . 4)))  => 4
(eval '(let ((z 5)) (pz)) t)  => (void-variable z)
(eval '(let ((z 6)) (pz)) '(z))  => 6

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