[plt-scheme] evaluating buffer w/o re-initializing environment?

From: Dave Herman (dherman at ccs.neu.edu)
Date: Sun Mar 29 14:54:55 EDT 2009

> I'm fine with Matthias's explanation above and at [1].  Sometimes 
> though, I wish I could hold on to, say, a database connection.

This sounds appealing, but -- I'm just conjecturing here -- it might 
turn out to be more trouble than it's worth. For example, if a database 
connection is represented as an instance of a struct, then re-running 
the program will generate a new, incompatible struct type. So even if 
you have persistent state stored in "cookies" somewhere, you won't 
actually be able to *use* your database connection.

Even if you use some kind of more transparent data structure, the data 
might be tied to some stateful code somewhere, possibly buried deep in 
some transitively required library, and the new instance of the program 
that has generated fresh state is probably not expecting to interact 
with leftover data from a previous instance of the program.

I suspect this is the kind of stuff that Matthias is talking about as 
causing extra unnecessary complexity that distracts even genius Lisp 


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