Proof of concept for v2 - NO duplication, NO `static if` hell, NO difficulty with interoperability

[Andrei Alexandrescu]

On 2021-10-31 23:34, zjh wrote:
> The C++ `concept` is also very convenient. When writing constraints on a 
> separate `T` type, there is no need to write an `if...` behind. With a 
> little effort, users can feel comfortable.

The problem with C++ concepts is that they invent yet another language 
on the top of the three C++ already has in it. It is a massive mistake, 
though not big enough to destroy the language. C++ continues to be 
successful in spite of it, not because of it.

The right way is to express concepts within the current language and 
algebra, as D does.