eq and hashing (was Re: [plt-scheme] How to make unit functors?)

From: Neil W. Van Dyke (neil at neilvandyke.org)
Date: Fri May 30 05:45:40 EDT 2003

Zbyszek Jurkiewicz <zbyszek at duch.mimuw.edu.pl> writes at 11:04 30-May-2003 +0200:
> On Thu, 29 May 2003, Matthew Flatt wrote:
> > Granted, this is not likely to be much of an issue in the absence of
> > malicious programs. But MzScheme is part of an experiment in protecting
> > against malicious programs.
> Wrong, we cannot protect against malicious programs, otherwise the 
> programming language would become too weak to be useful in practice.

That assertion surprises me.

> As for collecting symbols, in my opinion well-written programs
> do not construct dynamically a lot of interned symbols.

I sometimes shy away from interning arbitrary strings from an external
source in long-running programs, unless I'm confident they're GC'd.
(I cringe knowing that not all Scheme implementations that run HtmlPrag
can GC symbols.)

However, interning of these strings is often terribly convenient and
seemingly in the spirit of Lisp as a language for symbolic manipulation.
Consider the Lispy elegance of SXML, for a prominent example.

GC is all about guilt-free indulgences.


Posted on the users mailing list.