Spec#, nullables and more

[Walter Bright]

Rainer Deyke wrote:
> On 11/5/2010 17:41, Walter Bright wrote:
>> In other words, I create an array that I mean to fill in later, because
>> I don't have meaningful data for it in advance.
> 
> That's a faulty idiom.  A data structure that exists but contains no
> valid data is a bug waiting to happen - no, it /is/ a bug, even if it
> does not yet manifest as incorrect observable behavior.  (Or at best,
> it's an unsafe optimization technique that should be wrapped up in an
> encapsulating function.)

An example would be the bucket array for a hash table. It starts out initially 
empty, and values get added to it. I have a hard time agreeing that such a 
ubiquitous and useful data structure is a bad idiom.