[plt-scheme] starting DrScheme with no language level chosen

From: Gregory Woodhouse (gregory.woodhouse at sbcglobal.net)
Date: Sun Dec 4 15:17:30 EST 2005

On Dec 4, 2005, at 11:50 AM, Robby Findler wrote:

> The most frequent bug report we get (by far) is "DrScheme does not
> allow dotted pairs" or "DrScheme does not allow set!" followed by
> comments along the lines of "how can you call this 'scheme'" etc. The
> problem is, of course, that these people do not realize that they need
> to pick an appropriate language level. This next release is our new
> attempt to combat that problem. I suspect that hiding the message
> telling people to choose the language level probably would not work in
> our favor in this case.
> In partial answer to the use-case you mention below (where someone
> changes the language immediately, perhaps without even reading the  
> text
> at the bottom), you will note that anything do uses the new language,
> except type a program in the REPL but the REPL tells you that you
> should click Run to get your newly selected language.
> Robby

Being relatively new to Scheme (and certainly DrScheme), I often find  
myself wondering which language to use and, for that matter, what is  
standard and what is not. I only noticed this morning that if I  
choose "Swindle" then I can go ahead and use call/cc as a synonym for  
call-with-current-continuation (without defining it, that is). I  
still wonder about the letcc used systematically in "The Seasoned  
Schemer". I think I can manage to translate the examples, but it is a  
bit of an adventure trying to figure out what dialect you need, or  
how code needs to be modified before it can be run.

Gregory Woodhouse
gregory.woodhouse at sbcglobal.net

"Perfection is achieved, not when there is nothing more to add, but  
when there is nothing left to take away."
-- Antoine de Saint-Exupery

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