Re: r6rs libraries, round two

[Andy Wingo <wingo@pobox.com>]

Hey Julian,

On Sun 31 May 2009 01:22, Neil Jerram <neil@ossau.uklinux.net> writes:

> Julian Graham <joolean@gmail.com> writes:
>
>> 1. Add an optional `version' field to the module record type
>
> Sounds good.

Agreed.

>> * What's a good format here?  We could mirror the requirements of R6RS
>> here (i.e., (v1 v2 ...) where vx is a whole number) or be more
>> flexible.
>
> Given that your objective is to get R6RS library support in, I'd say
> just stick to the R6RS format for now.  It sounds like it will be
> fairly easy to extend this in future, if we want to.

Also agreed.

>> * Should we establish some rules for what you get when you don't
>> specify a version?
>
> Yes!  The latest available?

I don't know. To me this could be a distro decision, like Debian's
"alternatives" system. It would be nice to minimize the number of `stat'
calls it takes to load a library -- which would fall out nicely if when
asking for a module without specifying a version, like `(foo bar)', we
give foo/bar.scm.

In the presence of multiple versions, installation rules could handle
making the symlink so there is a default version -- typically the
version that was installed most recently.

>>  Given what we've decided about loading multiple
>> versions of a library (i.e., you can't)
>
> I didn't follow why we decided that, but it feels wrong to me.  (It
> seems to me that Guile should be able to handle loading ((foo) v1) and
> ((foo) v2) simultaneously as easily as it could handle loading
> ((foo-v1)) and ((foo-v2)) simultaneously.) I guess I should look up
> the previous thread, please let me know if you have a convenient
> reference.

I agree it would be nice, but as I said in the thread that Julian
referenced, that would take some more thought -- more than the R6RS
editors were willing to give the problem. And for us, I suspect we would
need some changes to our hierarchical namespaces. We probably shouldn't
let this be a sticking point for Guile's R6RS libraries support.

Regards,

Andy
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