DIP85: Lazy Initialization of const Members

[Marc Schütz via Digitalmars-d]

On Saturday, 14 November 2015 at 14:30:33 UTC, Marc Schütz wrote:
> http://wiki.dlang.org/DIP85
>
> This DIP proposes an officially sanctioned way to initialize 
> const members (or mutable members of const structs) lazily by 
> allowing limited mutation of const objects.
>
> Destroy!

I'm just right now reading Andrei's post on persistent lists, and 
I realize it can be even more useful if it supports immutable 
objects. I made some modifications to allow that.