reversed types can be byte_comparable, but in this case we should
invert the order of the comparation.
One alternative here, of course, would be to just declare all reversed types
non-byte comparable. That would definitely be safer, but at the expense of
always having more expensive comparisons for inverted orders.
Signed-off-by: Glauber Costa <glommer@cloudius-systems.com>
Also replace derived types (map_type, collection_type, etc.).
As we'll change data_type's definition, this reduces the number of places
that need to be modified later, and is more readable.
We didn't handle properly the case when the last component of a
prefixable compound was empty. Because we do not encode component's
length, we did not distinguish a compound with last element empty from
a compound without the last element.
The fix is to always encode lengths in prefixable tuples.
