[plt-scheme] Delay/force printing behavior in advanced studentlanguage

 I find:

#lang scheme
(define a (delay 2))
(force a)
a

Welcome to DrScheme, version 4.2.2.4-svn27oct2009 [3m].
Language: Module custom; memory limit: 800 megabytes.
2
#<promise!2>
> 
 Jos


----- Original Message ----- 
From: "Mark Engelberg" <mark.engelberg at gmail.com>
To: "PLT-Scheme List" <plt-scheme at list.cs.brown.edu>
Sent: Sunday, November 01, 2009 9:58 PM
Subject: [plt-scheme] Delay/force printing behavior in advanced studentlanguage


> Compare the printing behavior of delays in student languages versus
> the module language by executing the following code:
> 
> (define a (delay 2))
> (force a)
> a
> 
> In the module language:
> #<promise!2>
> 
> In the advanced student language:
> (delay ...)
> 
> Note that the way it prints in module language gives you information
> about the contents of the promise once it has been forced.
> It seems like the advanced student language should give at least as
> good information as the module language.
> Therefore, I would like to see it print as:
> (delay ...) before it is forced and
> (delay 2) once it has been forced.
> 
> Any particular reason it doesn't do this?
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