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

From: Matthias Felleisen (matthias at ccs.neu.edu)
Date: Sun Nov 1 19:09:24 EST 2009

This is PLT's friendliest way (as far as I know) of telling you that  
you changed something in the code base w/o re-running setup-plt. I  
know I know ... but I have no clue why this error message is like it is.

  $ setup-plt -l lang












On Nov 1, 2009, at 5:10 PM, Mark Engelberg wrote:

> It was pretty obvious how to change it, but now when I run advanced
> student language, I get:
> require: namespace mismatch; reference (phase 0) to a module
> "C:\Program Files\PLT\collects\scheme\private\kw.ss" that is not
> available (phase level 0)
>
> When I change the file back to the way it was, I get the same problem.
> So I'm thinking somehow I corrupted the various dependencies or
> compilation process.
>
> How do I rebuild everything to incorporate the changed file?
>
> Thanks,
>
> Mark
>
> On Sun, Nov 1, 2009 at 1:38 PM, Robby Findler
> <robby at eecs.northwestern.edu> wrote:
>> I don't think that there is any particular reason. The relevant
>> library is pconvert.ss, if you wanted to sort out how to change it.
>>
>> Robby
>>
>> On Sun, Nov 1, 2009 at 2:58 PM, Mark Engelberg <mark.engelberg at gmail.com 
>> > wrote:
>>> 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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>>>
>>
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