[caplisp-devel] Fwd: [e-lang] "Fixing" the Common Lisp package system

[David M. <ra...@gm...>]

Here ya go! -David

---------- Forwarded message ----------
From: Jonathan Rees <ja...@mu...>
Date: Aug 26, 2005 6:47 PM
Subject: Re: [e-lang] "Fixing" the Common Lisp package system
To: Kevin Reid <kp...@at...>, David Mercer <ra...@gm...>

(Not cc'ing e-lang for uninteresting reasons related to my incomplete
transition to new email client infrastructure. Feel free to forward
but change the email address to ja...@mu.... Sorry I haven't
followed the whole thread.)

I think this is a herculean task. Good luck. There are scores of
features in Common Lisp that show abysmal capability discipline. This
is one thing that led me to give up on it (I worked on the first
Common Lisp implementation, NIL) and do T and Scheme 48 instead. I
always had in mind the goal of running multiple mistrusting users in
a single address space, which is tantamount to capability security.
While this has never happened in a serious way, it would be very easy
to do a capability-disciplined Scheme 48 if anyone cared to. E.g.
pairs are mutable in Scheme 48, for compatibility with the Scheme
report, but it is easy to remove set-car! and set-cdr! from the
namespace with little change in functionality. (You'd have to rewrite
list-sort and some other things that use them internally.)

Let's see... you'll have to make GET local to a lexical namespace
somehow, and OPEN... and Lisp INTERN has the same problem that Java's
does - if you can detect the internedness of a string then
confinement is impossible. I guess you already ditched dynamic
binding, catch and throw, and the condition system. And there are
tons of things that are similar to GET in that they access global
state - logical pathnames, readtables, defsetf, properties on keyword
symbols, etc. Were you going to make packages be the atomic security
domain, so that each had its own GET and so on (in effect a separate
address space)?

I'm using Common Lisp now so the horrors of the package system and
the rest of the language are fresh in my mind. I think your eventual
language won't be recognizable as Common Lisp, but it will be much
improved.

Best of luck

Jonathan


--=20
"Nothing above represents the position or opinion of the University of
Arizona or the Dept. of Mathematics, so there! :-)"