<Jay_Reynolds_Free...@mac.com> wrote:
> > Aside from R5RS support, and multi-process support via shared memory,
> > does Wraith have any onboard facilities for extension, aside the
> > hacking the underlying implementation code directly?

>   Well ...

>   (1) I haven't released source code for the program.  (I have been
>       thinking about open-sourcing it, but it's kind of like letting
>       someone into your kitchen to watch you cook, and I'm kind of
>       nervous.)

>   (2) Lisp is pretty self-extensible in its own right; for example,
>       I am sure you could implement a class-definition and -
> instantiation
>       mechanism in any decent Scheme or in any other decent Lisp.

>   (3) Wraith Scheme has some built-in capabilities (as extensions, not
>       part of R5) to assist in inspection of its objects and data-
> structures
>       at low level, to assist in debugging, and to help with building
> up
>       communication and synchronization mechanisms for the parallel
> part
>       of the implementation (which provides only very low-level
> primitives,
>       but does so publicly, so users can build on them).

>   (4) One of Wraith Scheme's extensions is access to the C++ "system"
>       call -- you provide string X to Wraith Scheme and Wraith Scheme
> will
>       pass it to "system" as

>                     system( X ) &

>       "System" is awkward, and fussy to work with, but this extension
>       definitely gets Wraith Scheme out of its playpen.

>   (5) Along the development path that I personally plan for Wraith
> Scheme
>       are a number of other primitives for extension.  I am probably
>       tempting fate by mentioning them.  They include means to
> communicate
>       with devices on the Mac's USB bus (and if I do that I would
> probably
>       try to include means for Wraith Scheme to be interrupt-driven by
>       things happening on the bus), support for logic programming as
> in
>       Friedman, Byrd and Kiselyov's "Reasoned Schemer" (I would be
> careful
>       to respect their copyright and other intellectual property, of
>       course).  I would love to do a foreign-function interface to C++
>       but that's a huge project.

>   If there is something specific you have in mind or are interested
> in,
>   talk to me, either here or by EMail.

> --  Jay Reynolds Freeman
> ---------------------
> Jay_Reynolds_Free...@mac.comhttp://web.mac.com/jay_reynolds_freeman(personal web site)