This gist shows what Microstate helpers might look like using a callback to notify helper of change.

helpers_bool.js

import StateHelper from 'ember-microstates/helpers/state';
import { Bool } from 'microstates';

export default StateHelper.extend({
  construct(params, hash, onTransition) {
    return new Bool(params, onTransition);
  }
});

helpers_list.js

import StateHelper from 'ember-microstates/helpers/state';
import { List } from 'microstates';

export default StateHelper.extend({
  construct(params, hash, onTransition) {
    return new List(params, onTransition);
  }
});

helpers_num.js

import StateHelper from 'ember-microstates/helpers/state';
import { Num } from 'microstates';

export default StateHelper.extend({
  construct([value], hash, onTransition) {
    return new Num(value, onTransition);
  }
});

helpers_state.js

import Ember from 'ember';
import { State } from 'microstates';

export default Ember.Helper.extend({
  
  construct([Microstate = State], hash, onTransition) {
    return new Microstate(hash, onTransition);
  },
  
  compute(params, hash) {
    if (this._update) {
      this._update = false;
      return this._microstate;
    }

    let onTransition = (microstate) => {
      this._update = true;
      this._microstate = microstate;
      this.recompute();
    };

    return this._microstate = this.construct(params, hash, onTransition);
  }
});