Option!T

[Andrei Alexandrescu]

I talked to a programmer who knows Scala (among others) and he mentioned 
the usefulness of the Option type - a zero or one element collection 
(range in D terminology). Here's an article discussing it: 
http://danielwestheide.com/blog/2012/12/19/the-neophytes-guide-to-scala-part-5-the-option-type.html

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". Should we follow Scala's example and add it?


Andrei