Growing a Language (applicable to @attribute design)

[Walter Bright]

On 11/13/2012 12:56 PM, Walter Bright wrote:
> An insightful talk by Guy Steele on what makes a language successful.
>
> http://www.youtube.com/watch?v=_ahvzDzKdB0

Guy says something interesting in there that's applicable to one of our current 
discussions.

Particularly, should we allow:

    @identifier

as a user-defined attribute, in potential conflict with future reserved 
attribute words, or not?

Guy makes the argument that users need to be able to extend the vocabulary of a 
language and have those new words look like built-in ones. We have that today, 
of course, with the ability of defining new types. There is no special syntax 
that says "this is a user-defined type, not a keyword."

I think this is a compelling argument, and tips the scales in its favor. 
Probably we've been excessively worried about the problems of adding a new 
builtin attribute type.