Option!T

[qznc]

On Tuesday, 10 December 2013 at 18:15:58 UTC, Andrei Alexandrescu 
wrote:
> On 12/10/13 9:40 AM, JR wrote:
>> 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".
>>
>> Is this not what Nullable!T is?
>
> Nullable is not a range.

Nullable!T is a type for "a value of type T or nothing at all". 
It also provides a range interface if the T value is a range.

Where would you use an explicit zero or one element range?