Re: can't export conditional variable set with 'cond'

[Daniel Meißner]

Hi all,

Skyler Ferris writes:

> On 1/23/24 05:37, Mortimer Cladwell wrote:
> > When I run the above I get as output:
> >
> > "varB post cond: B"
> > "varC post if: C"
> > "varA in main: A"
> > "varB in main:"
> > "varC in main: C"
> >
> > Why can I reset the variables with both 'cond' and 'if' in env.scm, but
> > only the variable reset with 'if' is exported with the updated value?
> 
> I don't have a complete answer, but it looks like this has to do with 
> compilation. If I run it like this:
> 
> $ export GUILE_LOAD_PATH=$pwd
> $ guile main.scm
> 
> Then I see similar output, except that for me varC has also not been 
> updated. I am on guile version 3.0.9.
> 
> However, if I first set GUILE_AUTO_COMPILE=0 (and delete the cached 
> compiled modules) then the main module sees the updated values.
> 
> I'm not sure how imperative code in the top level of a module works when 
> compiling. It seems like a grey area.

I think this has something to do with compilation indeed. More specifically, it 
is caused by cross module inlining [1]. You probably need to declare your env 
module as not declarative by setting #:declarative? to #f inside the 
define-module form of env. I think the compiler inlines varB somehow. Not super 
sure, I am no Guile expert but you could inspect the assembly for main to see 
what the compiler did.

1: https://www.wingolog.org/archives/2021/05/13/cross-module-inlining-in-guile
2: https://www.gnu.org/software/guile/manual/html_node/Declarative-Modules.html

-- 
Best,
Daniel