Now again

[juan_gandhi]

1. a not totally trivial example implemented using JPA and Scala


2. an event sourced implementation using explicit state changes


3. a straightforward translation of the mutable event sourced implementation into an immutable implementation


4. encoding domain knowledge into the type system to make the domain easier to understand and reduce the number of runtime error checks


5. Towards an immutable domain model – monads (part 5) the stuff above translated into monads (where it should be)