Re: expression and definition context in Scheme

[Maxime Devos]

On 27-08-2022 21:02, Damien Mattei wrote:
> in fact just allow 'define that act locally ,see my comment below

I do not know what semantics you want.

>     Also, even if (begin ...) and (let () ...) where unified, it would
>     be a shame to lose the ability to only have some definitions
>     temporarily:
>
>     (define foo 0)
>
>     (let ((foo 0))
>       whatever-something-using-the-inner-foo)
>
>     something-using-the-outer-foo-again
>
> i do not propose foo to overwrite the global one

In that example, (define foo) might be global, but it might as well have 
been

(let ((foo 0))
  (let ((foo 0))
    whatever-something-user-the-inner-foo)
  something-using-the-outer-foo-again)

or

(let ()
  (define foo 0)
  (let ((foo 0))
    whatever-something-user-the-inner-foo)
  something-using-the-outer-foo-again)

I did not assume anything about global/local and wrote nothing about 
overwriting.
> , just to allow local define that have a local (in the block) range.

If with 'block' you mean the local (let ...) form, then this is already 
the case.

If not, maybe you are asking for Python-like lexical variables, but you 
have asked about that in the past -- it's a valid choice, but not Scheme.

If something else, you need to be much less vague and much more precise 
on what you want.

Greetings,
Maxime.

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