From: Taylan Kammer <taylan.kammer@gmail.com>
To: William ML Leslie <william.leslie.ttg@gmail.com>
Cc: Damien Mattei <damien.mattei@gmail.com>,
guile-devel <guile-devel@gnu.org>
Subject: Re: new function
Date: Thu, 23 Sep 2021 21:03:19 +0200 [thread overview]
Message-ID: <44ac5afd-24f3-df79-3b20-8c3645681163@gmail.com> (raw)
In-Reply-To: <CAHgd1hGM68sS+XJLqJYccVAxMZZYyHG=oSCyd1RzmasYcz6NAQ@mail.gmail.com>
On 22.09.2021 23:52, William ML Leslie wrote:
> On Thu, 23 Sep 2021, 4:51 am Taylan Kammer, <taylan.kammer@gmail.com <mailto:taylan.kammer@gmail.com>> wrote:
>
> On 22.09.2021 11:53, Damien Mattei wrote:
> > i already do it this way for internal defines ,using a recursive macro that build a list of variable using an accumulator. It can works but macro expansion seems slow, it was not immediate at compilation on a little example (oh nothing more that 2 seconds) but i'm not sure it is easily maintainable, it is at the limit what macro can do i think ,for speed reasons. In fact i can not really understand in Guile as it is based on C and compiled when macro expansion happens,what is the time cost... so for all those ,perhaps not objective reason ,i prefer to avoid.
>
> I don't think there's any other way to achieve what you want, especially
> using portable Scheme code. The lexical scoping semantics of Scheme are
> a very fundamental part of the language, and cannot be worked around in
> portable Scheme code without using a macro that rewrites whole bodies of
> lambda expressions.
>
> Even using implementation-specific hacks, you won't get very far. Any
> compiled Scheme implementation, and even most interpreted ones, won't
> allow you to modify an outer scope's set of variable definitions from
> within an inner scope.
>
> So if you really want to have Python's scoping semantics in Scheme, you
> will probably have to write a complex 'def' macro that walks through the
> body and "hoists" variable definitions to the outermost scope.
>
>
> Python is lexically scoped, and the assignment here is supposed to be local.
Well, yes and no. It implements variable hoisting, meaning all previously
unset variables that are set within a function are implicitly declared at the
beginning of the function. It doesn't have sub-scopes in function bodies.
--
Taylan
next prev parent reply other threads:[~2021-09-23 19:03 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 [this message]
2021-09-23 17:27 ` Damien Mattei
2021-09-23 18:00 ` Maxime Devos
2021-09-23 20:27 ` Taylan Kammer
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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