Option!T

[Wanderer via Digitalmars-d]

On Tuesday, 1 July 2014 at 20:34:05 UTC, Shammah Chancellor wrote:
> On 2014-07-01 12:45:11 +0000, w0rp said:
>
>> I'm also strongly in favour of Option/Maybe types in general, 
>> as a replacement for null. null is one of my pet hates, and 
>> things are much nicer when the lack of a value is represented 
>> in the type system. (T or Option!T)
>
> I would have disagreed with you in the past, but I just read 
> some examples from Rust and other languages with strong type 
> systems and I'm a convert.  I'd like to see a compiler flag to 
> turn off null assignment to reference types to enforce 
> Option/Nullable to be used.
>
> I also liked garbage collected pointers being expressed by the 
> type system.  Clarifies when libraries are expecting to take 
> ownership of a pointer, etc.
>
> -Shammah

Uhm, I'm sorry, but I don't see any difference between two 
approaches - null-not null vs. one value/no value.

In both cases, there is a possibility of a situation when the 
value that "should be there", is not there. It can be either 
because it's not available yet, or because programmer made a 
mistake in the code. But in either case, when you try to use the 
value that's "not there" without cheking first, you get a runtime 
error.

Correct me if I'm wrong, but "Option" being suggested here, is 
just a nullable reference in disguise.