[plt-scheme] Specifying choice of language/version in source file

On May 12, 2006, at 10:51 AM, Stephen Bloch wrote:

> Has anybody given thought to a way for a source file to specify which 
> DrScheme language it's intended to run in?

Yes. We have (had) a design (for quite some time) and Robby will 
eventually implement it. -- Matthias

> Or, for that matter, which version of DrScheme it's intended to run in?

P.S. Naturally this step must come after the first one, for validated 
annotations.

> On one hand, it's sometimes nice to be able to show what happens to 
> the same file in two different language subsets  or versions.  On the 
> other hand, that's not a common thing to need to do; much more common, 
> I suspect, is writing something which makes sense in a particular 
> subset/version and not in another.
>
> I guess if these specifications were part of the source file, they 
> would have to be in a syntax that's legal in ALL of the languages, and 
> I don't think there is any such thing.  So the alternative is to make 
> "intended language" and/or "intended version" a property of the file, 
> separate from the source code text.  It would presumably be lost (like 
> graphics) when one chooses "Save as text...", but it could be saved as 
> part of other files.  Would this make all such files (not just the 
> ones that contain graphics) unreadable by text tools?
> -- 
> 							Stephen Bloch
> 							Math/CS Dept
> Adelphi University
> sbloch at adelphi.edu
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