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Re: summary: lilypond, lambda, and local-eval
From: |
Hans Aberg |
Subject: |
Re: summary: lilypond, lambda, and local-eval |
Date: |
Fri, 16 Dec 2011 15:57:26 +0100 |
On 16 Dec 2011, at 13:43, David Kastrup wrote:
>>> Here's what I currently see:
>>>
>>> scheme@(guile-user)> (local-eval #'t (primitive-eval '(let ((t 42))
>>> (or #f (the-environment)))))
>>> ERROR: In procedure memoize-variable-access!:
>>> ERROR: Unbound variable: t
>>>
>>> This is the correct behavior, no?
>>
>> This is what I get when I play around with the following variation of
>> David's code in Guile 2.0.3:
>> (define (xxx)
>> (let* ((x 2))
>> (set! x (+ x 3))
>> (interaction-environment)))
>>
>> (eval '(begin (set! x (+ x 5)) x) (xxx))
>>
>> My guess (correct?) is that one wants some variation of
>> (interaction-environment) that can cause x in the eval expression to
>> bind to the environment returned by (xxx).
>>
>> Might eval be changed to accommodate for that (without introducing the
>> name local-eval)?
>
> It would likely help with unasking the question of what to do when
> (current-module) is different at the time of local-eval. I don't know,
> however, what the _lexical_ effects of switching the current module are
> supposed to be. If it is supposed to be a noop, then lexical
> environments and modules are presumably orthogonal, and eval should
> likely be allowed to take both (currently, local-eval is like taking a
> lexical environment and using primitive-eval in it).
Would you not it work as though you inserted code in the place where then
environment? - Then the syntactical rules should be captured as well.
In addition, there should be a way to communicate with the surrounding
environment, wherefrom the code is inserted. The only truly safe way would be
to make that explicit somehow, if not merely returning a value suffices.
Hans
- Re: summary: lilypond, lambda, and local-eval, (continued)
- Re: summary: lilypond, lambda, and local-eval, Andy Wingo, 2011/12/18
- Re: summary: lilypond, lambda, and local-eval, Noah Lavine, 2011/12/18
- Re: summary: lilypond, lambda, and local-eval, David Kastrup, 2011/12/18
- Re: summary: lilypond, lambda, and local-eval, Noah Lavine, 2011/12/18
- Re: summary: lilypond, lambda, and local-eval, Mark H Weaver, 2011/12/19
Re: summary: lilypond, lambda, and local-eval, Andy Wingo, 2011/12/16
- Re: summary: lilypond, lambda, and local-eval, David Kastrup, 2011/12/16
- Re: summary: lilypond, lambda, and local-eval, Mark H Weaver, 2011/12/16
- Re: summary: lilypond, lambda, and local-eval, Hans Aberg, 2011/12/16
- Re: summary: lilypond, lambda, and local-eval, David Kastrup, 2011/12/16
- Re: summary: lilypond, lambda, and local-eval,
Hans Aberg <=
Re: summary: lilypond, lambda, and local-eval, Ian Hulin, 2011/12/21