[plt-scheme] How to make unit functors?

From: Zbyszek Jurkiewicz (zbyszek at duch.mimuw.edu.pl)
Date: Thu May 29 10:49:39 EDT 2003

OK, there is a server, where people can leave private information.
The person who leaves the information uses some symbol as a key
for putting it into data structure.  Then, only people knowing
a key can get it.

The key is not stored in the datastructure, so someone reading the
datastructure information (by legal or illegal browsing of it) would not 
know to what key it belongs.

A little bit artificial, but useful. 

Zbyszek Jurkiewicz

On Wed, 28 May 2003, Matthew Flatt wrote:

>   For list-related administrative tasks:
>   http://list.cs.brown.edu/mailman/listinfo/plt-scheme
> At Wed, 28 May 2003 16:32:15 -0500, Robby Findler wrote:
> > Actually, this seems bad (or maybe just confusing?) -- it means that I
> > have to save not only the hash-code for an object; I also have to save
> > the object itself to ensure the hash-code doesn't change. Maybe this is
> > only really confusing for symbols?
> Can you give an example where an eq-hash-code is useful without its
> object? (Normally, you'd use a hash code to find the place in a data
> structure where the value is stored.)
> Matthew

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