rotten news relay - comp.lang.lisp - Re: History of lexical scope in Lisp

Subject: Re: History of lexical scope in Lisp
From: Didier Verna
Newsgroups: comp.lang.lisp
Organization: EPITA Research and Development Laboratory
Date: Sun, 17 Mar 2024 09:41 UTC
References: 1

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From: didier@didierverna.net (Didier Verna)
Newsgroups: comp.lang.lisp
Subject: Re: History of lexical scope in Lisp
Organization: EPITA Research and Development Laboratory
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Paul Rubin <no.email@nospam.invalid> wrote:

> Does anyone know when lexical scope started appearing in Lisp? Not
> counting Scheme, did it exist in predecessors of Common Lisp? Was it
> used much? Is it really true that Common Lisp had both lexical and
> dynamic scope in order to support older code that was written relying
> on dynamic scope and was too hard to convert?

That question should be answered by someone from the standardizing
committee, but anyway I think that there's two questions here.

Dynamic scope is necessary for some things (e.g. mutable global
variables, the condition system, thread-local storage, etc.), and then
there is the general user-level facility for declaring special
variables. So it might very well be that the original motivations for
those are different...

--
Resistance is futile. You will be jazzimilated.

Jazz site: http://www.didierverna.com
Other sites: http://www.didierverna.info

Subject: Re: History of lexical scope in Lisp
From: Lawrence D'Oliv
Newsgroups: comp.lang.lisp
Organization: A noiseless patient Spider
Date: Sun, 17 Mar 2024 21:12 UTC
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From: ldo@nz.invalid (Lawrence D'Oliveiro)
Newsgroups: comp.lang.lisp
Subject: Re: History of lexical scope in Lisp
Date: Sun, 17 Mar 2024 21:12:05 -0000 (UTC)
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On Sun, 17 Mar 2024 10:41:01 +0100, Didier Verna wrote:

> Dynamic scope is necessary for some things (e.g. mutable global
> variables, the condition system, thread-local storage, etc.) ...

Can’t see the reasoning behind any of those three examples. Thread-local
storage is the same as global variables, and global scope is just the
outermost lexical scope. As for the condition system, see my example
showing how a lexically-scoped language like Python can handle that.

Q: What is green and lives in the ocean? A: Moby Pickle.

comp / comp.lang.lisp / Re: History of lexical scope in Lisp

Subject	Author
Re: History of lexical scope in Lisp	Didier Verna
Re: History of lexical scope in Lisp	Lawrence D'Oliveiro