Another new io library

[deadalnix via Digitalmars-d]

First, I'm very happy to see that. Sounds like a good project. 
Some remarks:
  - You seems to be using classes. These are good to compose at 
runtime, but we can do better at compile time using value types. 
I suggest using value types and have a class wrapper that can be 
used to make things composable at runtime if desirable.
  - Being able to read.write from an io device in a generator like 
manner is I think important if we are rolling out something new. 
Literally the only thing that can explain the success of Node.js 
is this (everything else is crap). See async/await in C# 
(https://msdn.microsoft.com/fr-fr/library/hh191443.aspx) or Hack 
(https://docs.hhvm.com/hack/async/introduction).
  - I like the input range stuff. Input ranges needs more love.
  - Please explain valves more.
  - ...
  - Profit ?