Option!T

[monarch_dodra]

On Tuesday, 10 December 2013 at 17:28:26 UTC, Andrei Alexandrescu
wrote:
> We have only(x) (http://dlang.org/phobos/std_range.html#.only) 
> to be a collection of exactly one value, but not a type for "a 
> value of type T or nothing at all"

Option is being upgraded to handle an arbitrary (but compile time
known) amount of values:
https://github.com/D-Programming-Language/phobos/pull/1743