Guile virtual machine targets

[Ewan Higgs]

Hi all,
With Noah's suggestion of moving the Guile vm in a direction to support CLisp 
work as well, I became curious about the status of the various Guile back ends 
(Lightning and Guile-vm). These questions are largely out of personal interest 
and not leading up to any particular piece of work I had in mind.

Is Lightning actually supported? I saw that there is some mention of it on the 
old CVS page[1], but almost nothing else. I also see that Noah was working on 
something last year but it doesn't appear to have gotten into the master repo 
[1]. Is Lightning embeddable? If so, then I guess that work could replace the 
existing libguile virtual machine.

CLisp is currently using Lightning as of 2.45 (2008/02/24)[2]. So if Guile and 
CLisp are using this then would Noah's interests be satisfied? If Lightning 
doesn't provide enough features to support work that Guile's vm does, would it 
make sense to port the work for the Guile-vm to Lightning instead and simply 
support that back end?

If Lightning isn't embeddable, is LLVM? If so, wouldn't that become an 
attractive target for Guile as it's well documented and has a lot of inertia?

Thanks!

-Ewan

[1] As mentioned here: http://www.gnu.org/s/guile/anon-cvs.html -- though CSV 
is 
no longer used.
Noah has some work here): https://github.com/noahl/guile-lightning
[2] http://www.clisp.org/impnotes.html

NB: This was intentionally not cross posted to Clisp developers list.