futures and related asynchronous combinators

[Vlad Levenfeld via Digitalmars-d-announce]

https://github.com/evenex/future/

I've been having to do a lot of complicated async work lately 
(sometimes multithreaded, sometimes not), and I decided to 
abstract a some patterns out and unify them with a little bit of 
formalism borrowed from functional languages. I've aimed to keep 
things as simple as possible while providing a full spread of 
functionality. This has worked well for me under a variety of 
use-cases, but YMMV of course.

Anyway I've occasionally seen people on IRC asking about futures, 
so I thought I'd share and make this announcement.

This lib depends on another lib of mine (for tagged unions and 
related things) which might not appeal to some but if there is 
demand for futures sans dependencies I can always go back and 
manually inline some of the templates.

TL;DR:

   auto x = async!((y,z) => y + z)(1,2);
   x.await;
   assert(x.result.success = 3);