es

es.java

public interface State<T_state extends State> {
  void load(History<T_state> history, int lastTransaction);
}

public abstract class BaseState<T_state extends State> implements State<T_state> {
  private int lastTransaction = -1;
  @Override public void load(History<T_state> history, int lastTransaction) {
  }
  
}

public interface History<T_state extends State> {
  List<Transaction<T_state>> getTransactions();
}

public interface Transaction<T_state extends State> {
  List<Change<T_state>> getChanges();
}

public interface Change<T_state extends State>{
  Change<T_state> apply(T_state s);
  void unapply(T_state s);
}