ImmutableCursorStore.js

var structure = immstruct({turtles: []});

var TurtlesComponent = React.createClass({

  componentWillMount: function() {
    this.setState({turtlesCursor: structure.cursor()}

    structure.on('swap', () =>
      this.setState({turtlesCursor: structure.cursor()}));

  },

  onAddButtonClick: function(e) {
    this.state.turtlesCursor.updateIn('turtles', (turtles) => 
      turtles.push(e.target.turtle)
    );
  },

  renderTurtleCount: function() {
    return <div>{this.state.turtlesCursor.deref().size}</div>;
  }

});