From: Taylan Kammer <taylan.kammer@gmail.com>
To: Damien Mattei <damien.mattei@gmail.com>
Cc: Jean-Paul Roy <jean-paul.roy@unice.fr>,
guile-devel <guile-devel@gnu.org>
Subject: Re: new function
Date: Thu, 23 Sep 2021 22:27:31 +0200 [thread overview]
Message-ID: <9c058f24-5b15-417a-17ff-10bc13fed12d@gmail.com> (raw)
In-Reply-To: <CADEOadePDXQJZgQJG1oK9Bj16EaY2zGs+OBYauj=E0sUf8Pg9g@mail.gmail.com>
On 23.09.2021 19:27, Damien Mattei wrote:
> yes i know parsing the whole code is the only portable solution, but it is slow,even on a few dozen of lines the slowing is visible ,so i can even think of that on one thousand lines...
>
> I finally succeed in Guile with simple piece of code to make my example run with a single assignment operator <- , here i define for variable the assignment operator <$ , <- is working with arrays too:
>
> *Preview:*
>
> (define-syntax <$
>
> (lambda (s)
>
> (syntax-case s ()
>
> ((_ var value)
>
> (case (syntax-local-binding #'var)
>
> ((lexical) #'(begin
> (display "<$ : lexical scope : ")
> (display (quote var))
> (newline)
> (set! var value)))
>
> ((displaced-lexical) #'(begin
> (display "<$ : displaced-lexical scope : ")
> (display (quote var))
> (newline)
> (set! var value)))
>
> ((global) #'(begin
> (display "<$ : global scope : ")
> (display (quote var))
> (newline)
> (define var value)))
>
> (else #'(begin
> (display "<$ : unknow variable scope :")
> (display (quote var))
> (error "<$ : unknow variable scope : "))))))))
>
I can't seem to find syntax-local-binding in Guile 2.2 or 3.0. Did you
have to import some special module, or are you using another version?
Either way, I suspect that the following will not work with your macro:
(let ()
(let ()
(<$ x 1))
(display x)
(newline))
If I understand correctly, it will expand to:
(let ()
(let ()
(define x 1))
(display x)
(newline))
And that won't work because 'x' is only defined in the inner 'let'.
This is where we see the crucial difference between Scheme and Python:
in Python there is nothing similar to an inner 'let'. There is only
one function-level scope. In Scheme, there can be as many nested
scopes as you want, and an inner scope can't affect an outer one.
--
Taylan
next prev parent reply other threads:[~2021-09-23 20:27 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-19 7:54 new function Damien Mattei
2021-09-19 14:41 ` Matt Wette
2021-09-19 14:43 ` Matt Wette
2021-09-19 21:38 ` Taylan Kammer
2021-09-21 12:26 ` Damien Mattei
2021-09-22 8:44 ` Damien Mattei
2021-09-22 9:06 ` William ML Leslie
2021-09-22 9:53 ` Damien Mattei
2021-09-22 18:51 ` Taylan Kammer
2021-09-22 21:52 ` William ML Leslie
2021-09-23 8:40 ` Damien Mattei
2021-09-23 19:03 ` Taylan Kammer
2021-09-23 17:27 ` Damien Mattei
2021-09-23 18:00 ` Maxime Devos
2021-09-23 20:27 ` Taylan Kammer [this message]
2021-09-23 20:42 ` Damien Mattei
2021-09-23 20:48 ` Taylan Kammer
2021-09-23 21:53 ` Damien Mattei
2021-09-24 4:41 ` Damien Mattei
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