[racket] c extensions and embedding

I agree that extensions should be more explicitly discouraged in favor
of the FFI.

Embedding could be similarly discouraged. While embedding is probably
still as useful as ever, it was never especially useful.

I'll revise the Inside manual.

At Wed, 04 Sep 2013 00:07:41 -0400, Neil Van Dyke wrote:
> In the documentation, would it be a good idea to discourage the use of C 
> extensions and embedding of Racket (in the old Inside MzScheme senses of 
> "extension" and "embedding")?
> 
> I have been discouraging their use for a few years now.  I think they 
> made more sense when mzscheme was smaller, was slower, used the CGC, and 
> did not have an FFI.  Today, extensions and embedding seem like a last 
> resort, when one has ruled out all other approaches.
> 
> This seems like one of those things that is likely to derail potential 
> new Racket adopters: they pick a poor approach that initially (according 
> to documentation) seems viable, they run into difficulty, and they might 
> give up on the entire platform.
> 
> Or, if extensions and/or embedding work better today than I thought they 
> do, then my mistake, and I withdraw the suggestion.
> 
> Neil V.
> 
> ____________________
>   Racket Users list:
>   http://lists.racket-lang.org/users