[plt-scheme] v4 language levels

From: Matthew Flatt (mflatt at cs.utah.edu)
Date: Sat Feb 2 18:40:07 EST 2008

[Chiming in with Robby's reply...]

At Sat, 2 Feb 2008 16:41:24 -0500, Aleks Bromfield wrote:
> Right now, v3.99.0.9 has two separate methods for choosing a language:
> the old way (the Choose Language menu), and the new way (#lang). So, a
> few questions:
> 1. Are these two mechanisms going to be reconciled when v4 is released?

No. These two mechanisms will stay in place, as they were through the
v2xx and v3xx series.

As Robby suggests, we do intend to use `#lang' with `Module' more and
more, since we're gradually figuring out how to make things work

For example, I used to use the MzScheme, MrEd, and Pretty Big languages
in DrScheme frequently. Now I rarely use them, because it's usually as
easy to add `#lang scheme' to my program as it is to use the
choose-language dialog.

> 2. Is the old language<%> interface sticking around, or going away?

As Robby says, that's staying.

> 3. Will there be a way for students to use teaching languages without
> having to use #lang?

Same as always. Beginner, Intermediate, Advanced, and EoPL, among other
languages, will stay in place, and you can plug in new languages
suitable for teaching.

> 4. Is there (or will there be) a guide on porting languages from the
> old style to the new style?

That's a good question. We have been talking about the need for a guide
on the topic of building languages and tools. The main thing holding
that up is all the other docs we need to write.

> 5. Is any of this worth worrying about now, or might this all change in
> unknown ways before v4 is released?

I doubt that there will be more major changes for v4. We have a lot of
docs to finish, some libraries to expand (e.g., `scheme/list)', and
R6RS support to build --- but those are just completions, library
additions, and straightforward refinements to what we have in

Then again, all of that will take a few months, which is time for new
and better ideas.


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