immutable-vs-seamless.js

// Immutable() when using seamless-immutable; Immutable.fromJS() when using ImmutableJS
const initialState = Immutable({
  todos: {
     'a': { id: 'a', description: '...', isComplete: false },
     'b': { id: 'b', description: '...', isComplete: false }
  }
})

const reducer = (state, action) => (
  state.setIn(['todos', action.todoId, 'isComplete'], action.payload)
)