PKValue

[KyGost]

Representing primary keys as a more concise type than Value, such that stored values are actually hashable and safely unique might be a good idea.

Floats and nulls wouldn't be allowed.

Strings probably wouldn't be allowed?
(?)-- requires allocation, unsized. Either could be allowed or maybe could be converted to a limited size?

[KyGost]

Reasons why this might not be a good idea:

• is there much benefit?
• is conversion cost a concern?

[KyGost]

Prehaps PKValue should be an alias or a wrapper, without type info.
Stored as [u8; 8] or u64

[KyGost]

Per #144, implement PKValue as a trait/enum and implement TryFrom<Value>

[KyGost]

Should be implemented as a trait which gives Into<[u8; 8]> and CAN_PK