[atmin]

Thanks for the insightful explanation. Adding https://github.com/atmin/freak to the comparison (disclaimer, I'm the author):

* it supports set operations, `model(‘fieldName’, newValue)`, like Backbone and unlike Redux, which trigger only the necessary update actions in the (implicitly built) dependency graph. set is idempotent, even if your computed properties have side effects

* it has .on() method

* "You can log every action and see the entire state tree before and after the action.”. In freak, too:

    const model = freak(statePOJO);
    const history = [];
    model.on(‘change’, prop => {
      // change is called exactly once per mutation
      history.push({...model.values});
    });

freak’s README is a literal test suite, consisting of state changes and assertions.

Probably it's a good idea to add 'beforeChange' event, to make it possible to cancel a mutation.

* it's currently implemented internally using mutable data structure, but this is implementation detail and can be changed to immutable data in the future, allowing simply `history.push(model.values)`