a new contract for reference types

Peter Levart peter.levart at gmail.com
Wed May 8 06:37:18 UTC 2019


On 5/2/19 12:29 AM, John Rose wrote:
> Regarding subtyping, I don't see (from these considerations)
> a firm reason to declare that V? is a super of V.  The value
> set of V?*might*  have one more point than that of V,
> or it*might not*.  The reason we are doing V? is not the
> value set, but the whole contract, which includes the
> value set as an obvious, but ultimately non-determinative part.

Just one observation...

If inline class V was declared to support a "kind" of null (default, 
sentinel) value by itself, then how such value would be denoted?

Is this a way?

V v = null;

If this was possible, then what would be the distinction between the 
following two then?

V? vInd1 = null;
V? vInd2 = v;

Would vInd1 and vInd2 represent the same "null" value?

Regards, Peter

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