null and type safety

[Robert Fraser]

Walter Bright wrote:
> Jarrett Billingsley wrote:
>> Dereferencing a null pointer is *always* a bug, it doesn't matter how
>> "safe" it is.
> 
> Sure. But I'm interested in creating a safe subset of D, and so the more 
> correct interpretation of what constitutes "safety" is important.
> 
>> Don't you think that eliminating something that's
>> always a bug at compile time is a worthwhile investment?
> 
> Not always. There's a commensurate increase in complexity that may not 
> make it worth while.
> 
> My focus is on eliminating bugs that cannot be reliably detected even at 
> run time. This will be a big win for D.

FWIW, I've _never_ run into a bug const could have prevented. OTOH, I've 
often run into bugs that non-nullable types could have prevented 
(including one on a production system... well, there was another bug 
that raised an exception causing something else to be uninitialized and 
the system came crashing down).