lispOS and persistent store

Luca Pisati
Tue, 29 Apr 1997 18:02:24 -0700

David Gadbois wrote:
>    Date: Fri, 25 Apr 1997 19:33:11 -0700
>    From: Luca Pisati <>
>    I'm just trying to understand what are we trying to do here.
> It is totally up in the air.  The are lots of exciting ideas floating
> around.  Until someone sits down and actually does something, we are
> mapping out the possibilities and arguing the benefits of various
> approaches.  At some point, we'll need to articulate clear goals so
> that we can get good work done and so newbies can get up to speed
> quickly.
>    1. A Lisp-Machine (a full featured Lisp based OS, with
>       classic OS structure: file-system, network ....),
>       running directly on some hardware, or lying on top
>       of some kernel.
> This is what I would like to see.  A single, object-oriented address
> space where every capability is just a pointer dereference or a
> function call away.

Yes, but, how can you solve problems as efficient tags,
without a tagged bit architecture, for instance ?

I worked on XL's and I do work now on commercial computer
graphics software (90% in CL/CLOS/MOP) running under ACL on IRIX.

We do sell our software, and since it is for real-time market,
we have to run it fast and efficiently.  I spent a lot of time
optimizing code to avoid "boxing" of single-floats into a tag +
a pointer + a single float ... and so on ...

Can you really build a pure LispOs without a tagged architecture,
and then be prone to Lisp Objects inefficiency ?

Can you write efficient code not only for kind of software,
but also for numerically-heavy applications ... ?

>    2. A Virtual Lisp Machine, running on top of existing
>       OS and hardware.
> I'd like to view this as more of an engineering approach than a
> fundamental design issue.  As existence proofs, we have Open Genera
> and the various Smalltalk environments:  You hardly have to know that
> there is some kind of hypervisor between you and the metal.

Isn't it Open Genera emulating a 40bits (8 tag + 32 data) hardware
on top of a 64 bits machine (then wasting 24bits per word) ?

>    3. A Lisp based OS with radically new approaches as
>       substituting persistent objects to file system and so on ...
> This is the sizzle that makes the whole project so appealing:  The
> very ability to be able to consider such new ideas as "simple matters
> of programming" rather than as major political and organizational
> commitments.

The only problem is that compromises accepted for the sake of 1) and 2)
could make difficult (if not impossible) to maybe reach goal 3).

> --David

Luca Pisati		       Voice:	 (310) 577-0518
Nichimen Graphics	       Fax:	 (310) 577-0577
12555 W. Jefferson #285        EMail:
Los Angeles, CA 90066          Web: