Well mines : Unicode is trickier than you think, there are some date-time that don't exist, transactions are trickier than one (usually) think, don't use floati

Well mines : Unicode is trickier than you think, there are some date-time that don't exist, transactions are trickier than one (usually) think, don't use floating point for money (because many people don't understand floating point), a quick fix always introduces another bug, any contract (WSDL, json-schem, whatever) is full of holes, integrate with others first, legacy database are full of bad/unexpected data,...