Spec#, nullables and more

[Don]

Pelle Månsson wrote:
> On 11/05/2010 03:04 PM, Kagamin wrote:
>> Pelle Månsson Wrote:
>>
>>> Getting the error early is actually a lot better than getting the error
>>> late.
>>
>> OK, but it doesn't reduce the number of bugs. You had an error with 
>> nullables and you still has error with non-nullables.
> 
> But in the non-nullable version you actually know where the bug is, 
> namely where you assign the null to the thing that shouldn't be null. 
> The segfault can come from any unrelated part of the program whereto 
> your null has slipped, at any later point in time.

I've always found it very easy to work out where a null came from. What 
I would hope from a non-nullable type is to eliminate rare code paths 
where a null can occur, which might not show up in testing.