Automatic persistence

[matthewp]

Previously posted in the lyra repo:

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From an API perspective, if I was creating a persistence package, I would want the ability to persist on each change to the database. It might be nice if a lyra DB was an event emitter for that reason. I could imagine a disk persistence package working like:

const persist = (db, format) => {
  saveToDisk(db, format);

  db.addEventListener('change', () => {
    saveToDisk(db, format);
  });
};

That way a user would only need to call persist once and not manage calling it every time they inserted, removed, etc.