The NaN of types (in D)

[Joseph Rushton Wakeling]

On Sunday, 11 October 2020 at 20:37:56 UTC, Paul Backus wrote:
> On Sunday, 11 October 2020 at 19:45:06 UTC, Stefan Koch wrote:
>>
>> ø is a special case that shouldn't happen to often.
>>
>> You are free to ignore the possibility of it being null.
>> Just like with classes which almost no one checks with class 
>> is null.
>
> Given that null references for classes are widely considered a 
> "billion dollar mistake" [1], the comparison does not exactly 
> fill me with confidence.

Is that really a valid comparison, though?  Doesn't the issue 
with null references for classes stem from memory safety concerns?

I don't quite see how that applies in the case of types, any more 
than NaN is a safety issue for floating point numbers.