[plt-scheme] DrScheme buglet?

From: Robby Findler (robby at cs.uchicago.edu)
Date: Wed Aug 29 09:52:40 EDT 2007

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)

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.


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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