Add cardano-binary package about cardano-ledger-byron HOT 2 CLOSED

Hi @neongreen!

I agree, in many cases using TH or Generics would decrease the likelihood of bugs, and as an added bonus reduce the amount of code. In this specific case, with a binary serialisation format that might be subject to modification, being explicit means we can add backwards compatibility code to a specific instance or, if something goes wrong, the faulty code is right there for us to see. Also a newcomer to the code will be able to see how something is encoded/decoded without having to -ddump-splices. We do have to be more careful, but this is the code where we'd rather be explicit and careful.

from cardano-ledger-byron.

as it is better to have hand-written instances for that kind of thing

Well, this is rather questionable. TH was introduced exactly to avoid hard-to-avoid bugs that can occur with hand-written instances.

from cardano-ledger-byron.