The Sparrow language

[Kagamin via Digitalmars-d]

On Wednesday, 6 April 2016 at 13:15:48 UTC, Andrei Alexandrescu 
wrote:
> Another feature we could consider adding to D is a simple 
> definition of concepts as complex Boolean predicates. That's 
> essentially identical to isForwardRange etc. etc. but makes for 
> simpler use of these predicates.

Anyway it's a new level of type system. Does D still accept new 
features of such complexity?