[gambit-list] Gambit roadmap

Hendrik Boom hendrik at topoi.pooq.com
Tue Jul 19 22:10:28 EDT 2011

On Tue, Jul 19, 2011 at 08:04:36PM -0500, Jason E. Aten wrote:
> >
> > On Tue, Jul 19, 2011 at 4:29 PM, Hendrik Boom <hendrik at topoi.pooq.com>wrote:
> > The C-- project has some ideas how to manage the interface between a GC
> > and its language.  They may be right on how to do it, but I don't think
> > their interfacing has yet been tested on anything parallel.
> >
> > -- hendrik
> >
> This is an interesting comment.  I concur with Marc that C-- looks to be
> dormant, especially now that Haskell has its LLVM backend.

I didn't know that Haskell had gone to LLVM.  

> But I'm not particularly impressed with how LLVM handles garbage
> collection.  If you don't mind my asking, what specifically
> about C--'s approach to GC/language interface did you find particularly
> compelling?

MAybe the fact that they managed to integrate a mostly untyped langauge 
with a garbage collector that needs to knoww types.  That they actually 
addressed the issue in their language design instead of ot looking like 
a total afterthought.  And that they expect the C-- code generator to 
keep track of all the transient values in registers or wherever so that 
the garbage collector can actually get the information it needs to do 
its job.  That, and that they've provided an interface to the write 
barrier that modern concurrent garbage collectors need to get any kind 
of speed.  This stuff was designed in.

So the garbage collector can get, say, pointers to type-descritprs for 
the stuff on the stack.  But as to what the type descriptors actually 
are, well, that's a matter between the high-level language and the 
garbage collector.  C-- doesn't involve itself with it.  I'm not sure 
whether this is a pity or not.  A lot of the really tricky aspects of 
garbage collection don't care much about the details of the language.  
It would be useful to have that part available, only to be 
paranmetrized with the methods for interpreting type descriptors.
It would be useful for that part, as a result, to be able to deal with 
the specific data layouts of different languages when they're used 
together in one program.

-- hendrik

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