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Re: Re: intern a top level variable
From: |
tomas |
Subject: |
Re: Re: intern a top level variable |
Date: |
Wed, 16 Aug 2023 19:58:54 +0200 |
On Wed, Aug 16, 2023 at 06:13:05PM +0200, Jean Abou Samra wrote:
> Le mercredi 16 août 2023 à 10:55 -0400, Mortimer Cladwell a écrit :
> > I would like to intern and assign a value within a method:
> >
> > (define (test-intern)
> > (let* ((name "abc")
> > (data "def")
> > (name-symbol (gensym name))
> > )
> > (pretty-print (string-append "symbol: " (symbol->string name-symbol)))
> > (set! name-symbol data)))
> >
> > scheme@(guile-user)> (test-intern)
> > "symbol: abc3301"
> > scheme@(guile-user)> abc3301
> > ;;; <unknown-location>: warning: possibly unbound variable `abc3301'
> > ERROR: In procedure module-lookup: Unbound variable: abc3301
>
>
> Sorry, but it's not clear to me what you mean by "intern and assign a value",
> and I don't think it will be clear to someone else.
>
> Can you be more precise please?
I think what the OP wants is to make a binding for
an existing symbol. Something, perhaps like
scheme@(guile-user)> (define foovar (gensym "foo"))
scheme@(guile-user)> foovar
$1 = foo170
scheme@(guile-user)> (module-add! (current-module) foovar (make-variable 42))
scheme@(guile-user)> foo170
$2 = 42
(note that the "top level" is Just Another Module).
Mortimer: is that what you were looking for? Note that
"you usually don't do this" (whatever that means), so
it'd make sense to take a step back and think about what
you are trying to achieve :-)
> I don't understand why you expect "abc3301" to be bound after running (test-
> intern). That (test-intern) call just creates a symbol, which is interned as a
> symbol, meaning that creating another (interned) symbol with the same name
> will
> reuse the same symbol value. But there is no reason why it shoud be bound to a
> variable. Symbol interning just applies to symbols as values, it has nothing
> to
> do with variables.
In any case it would make sense to revisit the concepts
of "symbol", "variable" and "binding". It's subtle, but
in Lispy lands it is indispensable.
Cheers
--
t
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