Support MessagePack for Keys & Values (just a comparison function)

[erthink]

Actually only a comparison function for arbitrary msgpack messages is required.

[plq]

Why doesn't memcmp() work? What exactly do you need?

[erthink]

Why doesn't memcmp() work?
What exactly do you need?

MsgPack is (mostly) self-described data format.
Therefore, the comparison function for arbitrary msgpack messages allows you to compare many data types with due account it's semantics, including tuples.

For example, this allows you to order set of values of different types: boolean, double, int32, uint64, float, and so on, by the single comparison function.