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From: colas@avahi.inria.fr (Colas Nahaboo)
Newsgroups: comp.lang.scheme
Subject: Re: what is lisp, instead?
Message-ID: <1990Aug16.103617@avahi.inria.fr>
Date: 17 Aug 90 08:00:17 GMT
References: <9008132139.AA11205@mailhost.samsung.com> <9008141823.AA08641@satchmo>
Sender: news@mirsa.inria.fr
Reply-To: colas@avahi.inria.fr (Colas Nahaboo)
Organization: Koala Project, Bull Research France
Lines: 28

In article <9008141823.AA08641@satchmo>, rees@parc.xerox.COM writes:
> Or do you have some other way of dealing with the situation where
> (assuming left-to-right argument evaluation in C)
>   - the result of f is consed
>   - the only pointer to this result while in g is on the C stack
>   - invoking g triggers a GC
>   - after the gc g does more allocation, thereby overwriting the
>     result of the call to f? 

In wool (the lisp interpreter I designed for gwm), I use an original
time-based
GC: a gc only garbage-collects objects whose GC count came to 0 more recently
than the current stack frame was entered. Then in the case "equal(f(x),g(y))"
a GC in g won't try to gc objects created by f, which are "older" than the
invocation of g. This scheme avoids to bother the C programmer with any
GC_protect type of calls.

PS: gwm is an emacs-like WIndow Manager for X: it has a built-in lisp
interpreter for customization, fast and small, and totally C-compatible,
written in C. (and ~ 3 times faster than xlisp and emacs lisp).

PPS: wool was designed to be a library for C programmers, and to be as easy and
natural as possible to use from C.

--
Colas Nahaboo, Bull Research France -- Koala Project -- GWM X11 Window Manager
colas@avahi.inria.fr            Phone: (33) 93.65.77.70, Fax: (33) 93 65 77 66
INRIA - Sophia Antipolis, 2004, rte des Lucioles, 06565 Valbonne Cedex, FRANCE