[plt-scheme] DrScheme buglet?

From: Matthias Felleisen (matthias at ccs.neu.edu)
Date: Fri Aug 31 11:31:27 EDT 2007

I second Ryan's proposal.

On Aug 29, 2007, at 11:17 AM, Ryan Culpepper wrote:

> On Wed, 2007-08-29 at 08:52 -0500, Robby Findler wrote:
>> This only happens when there are syntax errors, right? Not runtime  
>> errors?
>>
>> I think that's just a property of the way teachpacks work in the
>> current world. I'm not sure it is possible to get around that.
>>
>> Roughly, what's happening underneath the hood, is that the teachpack
>> is (an invisible) part of your program and, when your program is
>> syntactically malformed, no part of your program is available in the
>> REPL. For example, in this program:
>>
>>   (define x 1)
>>   unbound-id
>>
>> You won't be able to use "x" in the REPL. But, in this one, you will:
>>
>>   (define x 1)
>>   (first empty)
>>
>> I know that's not real help, but I hope it is at least explanatory.
>>
>> And maybe this will inspire someone (Matthew?) to think of a way  
>> to do
>> better, I'm not sure.
>
> Would it make sense to make that explanation part of DrScheme? That  
> is:
>
> When a syntax error occurs, print a message to the effect of "No
> definitions executed due to syntax error" in the interactions  
> window and
> lock the interactions editor.
>
> Or instead of locking the interactions, DrScheme could instead display
> one of those yellow highlighted messages (like "definitions out of  
> sync"
> is displayed now) before every interaction. That would let students  
> use
> the interactions window to stumble around trying out syntaxes until  
> they
> find the right one.
>
> Ryan
>
>
>> On 8/29/07, Todd O'Bryan <toddobryan at mac.com> wrote:
>>> In v371 of DrScheme, it appears that teachpacks don't "stick."
>>>
>>> When you first open a DrScheme window, even though it says that a
>>> teachpack is loaded, it's unavailable until you hit Run.
>>>
>>> That's not a big problem, but the teachpacks disappear if there's an
>>> error during a Run. In other words, if students are developing a
>>> function, hit run, and have an error, if they drop down to the
>>> interactions window to experiment, the functions provided by the
>>> teachpack are no longer available.
>>>
>>> The workaround is to comment out offending code in the definitions
>>> window, but this is kind of a pain.
>>>
>>> Todd
>>>
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