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

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

[Michael Heerdegen]

Hello Mattias,

> +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?

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)?  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?

TIA,

Michael.

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

[Mattias Engdegård]

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

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

[Michael Heerdegen]

Mattias Engdegård <mattiase@acm.org> writes:

> > 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.

Ok.  Should you find some time, maybe you could do that?

> > 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.

Is "dynamically bound" a good choice of language, then, or would
"dynamically binding" or something else (like "indicating that this
variable should use dynamic scoping" in the comment you mentioned) be
a bit clearer?

> 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

Thanks.  Ok, good, that's all as expected.


Michael.

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

[Mattias Engdegård]

23 okt. 2023 kl. 05.50 skrev Michael Heerdegen <michael_heerdegen@web.de>:

> Ok.  Should you find some time, maybe you could do that?

Certainly, now done. I also updated the manual entry for `eval` for accuracy.

Thank you for your kind and useful comments!

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

[Michael Heerdegen]

Mattias Engdegård <mattiase@acm.org> writes:

> Certainly, now done. I also updated the manual entry for `eval` for
> accuracy.

LGTM.  Thank you Mattias.


Michael.