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

From: Zbyszek Jurkiewicz (zbyszek at duch.mimuw.edu.pl)
Date: Fri May 30 05:04:46 EDT 2003

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.
Most we can hope is to provide right constructs for programmers
to use (as in Scheme ;-).  It is not hard to write a simple program
which tries to allocate infinite list, practically blocking other

As for collecting symbols, in my opinion well-written programs
do not construct dynamically a lot of interned symbols.  This was
a technique popular in Lisps with neither strings nor structures, when 
symbols with property lists were used instead of them.

Interning the symbol means it is somehow important for program, so 
I think real symbols tend to be used for long during session.  It would be 
however interesting to make some empirical research hoe frequently 
symbols are allocated and deallocated in short time.

Zbyszek Jurkiewicz

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