Growing a Language (applicable to @attribute design)

[Paulo Pinto]

On Wednesday, 14 November 2012 at 00:54:07 UTC, Walter Bright 
wrote:
> 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.

I think an example to watch is how Java has been evolving.

Since attributes were added to the language, new features tend to 
be introduced via new attributes (e.g. @Overload, @NotNull, ...) 
to avoid collisions with existing code.

While it makes sense from the backwards compatibility point of 
view, and Python3 is a good example people don't like rewriting 
legacy code, it leads to attribute definition explosion.

--
Paulo