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

From: Jos Koot (jos.koot at telefonica.net)
Date: Sun Mar 29 19:59:25 EDT 2009

I did my first programs on punched Hollerith cards for batch processing. 
This makes you think twice before designing and writing down a program. No 
interactive terminals in those days (except the operator's main frame 
control board, which I used once in order to interact (and the whole main 
frame went down within a few minutes. As the main frame went down more 
often, it apparently was not noticed, for I never received a reprimande. A 
short look into the so called 'dayfile' would soon have revealed my sinn) 
Easy access to tools that can help develop ideas about how to construct 
certain parts of your program are nice of course, but the most important 
part of programming has to be done in the head, probably with the help of 
paper and a pencil. Having too easy tools to try out little pieces of code 
interactively may lead to trial and error programming, horrible. In this 
respect HtDP does a good job, I think. It guides the student to think about 
what has to be done before actually entering the final code. And this code 
is to be entered in the definitions window, of course. Therefore I don't 
mind Run to reset DrScheme, on the contrary, I like it, for it makes me sure 
that the erroneuous past is completely forgotten (and all previously running 
user threads being killed!) Mho, Jos

----- Original Message ----- 
From: "Fred G. Martin" <fredm at cs.uml.edu>
To: "pltscheme" <plt-scheme at list.cs.brown.edu>
Sent: Sunday, March 29, 2009 6:20 PM
Subject: [plt-scheme] evaluating buffer w/o re-initializing environment?

> Dear PLT-Scheme'rs,
> One of the things I really miss in Dr. Scheme is the ability to add
> new definition bindings without losing the state of the global
> environment.  When you evaluate a buffer with F5 or Run, the world is
> reset and then the buffer definitions are evaluated and put back.
> Am I missing something easy, or is this a deep design decision?  I
> wish I could introduce my students to the Lisp programming methodology
> of iteratively building up the objects in one's world and the
> procedures for interacting with them.
> Fred
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