Re: The Guile license and the use of LGPL libs (like GMP).

[Rob Browning]

Marius Vollmer <address@hidden> writes:

> If it is not too much hassle, we should keep our current bignum
> implementation as the fall-back.  We might have a thin interface layer
> between libguile and GMP (as some SCM_I_BIGNUM_ macros say).  That
> interface could be tuned to be efficiently implemented by GMP, and
> straightforwardly but not necessarily efficiently implemented with the
> current stuff.  What I'm trying to say is that we should not make
> ourselves a lot of work to keep the fall back be efficient.

I think I can do this without too much trouble.  I'll go ahead and see
after I get the next beta out and start working on 1.7 again.

> That would be a solution, but somehow, I don't like it very much.  It
> can't hurt to ask.  I am a bit unsure about my own position here, so I
> would have to think about this a bit more.  I would ask RMS what he
> thinks about removing the exception from libguile and about adding the
> restriction to GMP. But I don't know yet in what direction I would
> argue myself...

I don't really like this option too much either, unless the FSF really
does consider Guile a Very Special Case.

> That would not be good.  GMP is the technically Right Thing to use,
> and it would be strange to refuse our 'own' software for its
> restrictive license terms, wouldn't it?

Agreed.

> [1] Somehow, it escaped me that the exception was not equivalent to
> LGPL.  I had this image in my head where the FSF were trying a new
> strategy since they didn't really seem to like the LGPL any more.  But
> I also _knew_ that the exception did not turn the GPL into the LGPL.
> If someone had asked me directly... :-/

Well, my recollecion is that Guile was intended to have a somewhat
special status.  Since the FSF kinda hoped for World Domination on the
extension language front, the goal was to make sure the license didn't
get in the way, but only with respect to that particular issue --
hence the exception.  I can see the point, but it does make things a
little more complicated when Guile wants to depend (at the direct
linking level) on anything else.

Lets see how hard it is for me to get a --without-gmp fallback
working.  If I can, then we can probably just put a note in LICENSE
and forget about it for now.  I'll have to see how to best arrange
this.

Anyone here familiar enough with goops to know if we might be able to
handle bignums via goops with sufficient efficiency?  I kinda doubt
it, but I was wondering.  In any case I want to see if there's a way
to refactor the numerics so that the bignum code is less tangled with
the rest.  I'm not sure it's possible without too much loss of
efficiency, but I'll check.

-- 
Rob Browning
rlb @defaultvalue.org, @linuxdevel.com, and @debian.org
Previously @cs.utexas.edu
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