Re: primitive eval with module => Unbound variable?

[Jan Nieuwenhuizen <janneke@gnu.org>]

Andy Wingo writes:

> On Tue 16 May 2017 23:59, Jan Nieuwenhuizen <janneke@gnu.org> writes:
>
>> This code works when not put in a module; make it a module and I get
>>
>>     => ERROR: Unbound variable: bar
>
> I assume you mean that this doesn't work:
>
>   (define-module (foo) #:export (baz))
>   (define bar 42)
>   (define (baz) (primitive-eval 'bar))
>
>
> Then from another module you do (use-modules (foo)) and try to (baz).

Yes.

> The thing is that primitive-eval evaluates its expression with respect
> to the current module.  The current module when you do (use-modules
> (foo)) isn't (foo) -- it's the importing module.

Okay...

> This is the right thing:
>
>   (define-module (foo) #:export (baz))
>   (define eval-module (current-module))
>   (define bar 42)
>   (define (baz) (eval 'bar eval-module))

Thanks!...this works.  I'm very happy with this, it means that I can
create an sexp-object format, yay!

Earlier I tried several things eval, but did not see this `define
eval-module' coming.  The above works, this does not work

   (define-module (foo) #:export (baz))
   (define bar 42)
   (define (baz) (eval 'bar (current-module)))

and neither does this work

   (define-module (foo) #:export (baz))
   (define bar 42)
   (define (baz . args) (let ((eval-module (current-module))) (eval 'bar eval-module)))

So (current-module) is not the defining model (foo) in these cases.

Greetings,
janneke

-- 
Jan Nieuwenhuizen <janneke@gnu.org> | GNU LilyPond http://lilypond.org
Freelance IT http://JoyofSource.com | Avatar® http://AvatarAcademy.com