Motivation for compile time function execution

[Walter Bright]

Sean Kelly wrote:
> I think this is a fantastic feature.  It uses plain old D syntax and 
> offers all the computational power of templates.  Will this work for 
> template functions that follow the rules as well?

Yes.

> Also, is there any 
> way to test whether a function is being executed at run time?

Yes, it will be always executed at runtime if it is not in a context 
where it is required to be folded to a constant.