Immutable things.

[David Gadbois]

   From: "Dwight Hughes" <dhughes@intellinet.com>
   Date: Tue, 13 May 1997 11:24:45 -0500

   There are many reasons to have a lean, mean, lower-level, lighter
   weight Lisp for the kernel -- not just for programming the OS, but
   for everyone that will write a device driver, a real time control
   program, a new GC, a signal processor, ....

I really don't understand this "small is good" valorization.  The real
beauty part of the lisp machines is that there is no boundary between
the "kernel" and "application" code.  Sure, you have to be more
careful writing device drivers, the scheduler, the storage system,
etc., but I think the LispOS should cater to making it easier to write
ambitious applications rather than making it easier to write the
hardware support.  The payoff in applications for doing the hard work
to make the system as a whole correct, consistent, and usable vastly
outweighs the one-time costs of system implementation.

Also, for example, the Linux kernel can fit on a 3.5 inch floppy.
(Well, it can if you don't include too many drivers.)  But in order to
do anything actually useful with it, you need 200 MB worth of stuff in
/usr.  A 30 MB Genera world load still has a lot more functionality
and is vastly more usable.  By making the kernel small, you make
everything else huge.  What benefit is there to that?

--David Gadbois