Event sourcing is a method of immutable data storage, starting from a simple idea—instead of storing the current state of the world, what if we stored all the events that lead to the current state? The advantages of this approach are many and interesting—the ability to move forward and backward in time, built-in incremental backup, and thinking in a timeline rather than in a state. It also comes with a few caveats—deleting past data is very difficult, the event schema is difficult to change, and referential integrity tends to become looser. You also need to pay attention to possible errors and define policies for treating them in a structured and repeatable manner.
We've also seen how a simple event sourcing architecture can be implemented with the help of lambdas as events. We could also look at event sourcing for storing lambdas, since a stored...