[sealed] Sealed local classes?

[Maurizio Cimadamore]

On 10/10/2019 01:50, Brian Goetz wrote:
> Right. We already restrict anon and lambda instances of the sealed 
> type. Not only can't we stably write down their types in the PS 
> attribute, but even if we could, it's so easy to accidentally lose 
> exhaustiveness. 

This is a very good point; if I have type T = A | B | C, but then I have 
'anonymous' Ts flying around, all switches assuming A|B|C are no longer 
exhaustive.

Maurizio