gistfile1.js

store Tasks {
  @tasks = []
  @undone <- @tasks.filter(task => !task.done)

  makeTask(task) { return { title: title, done: false } }

  addTask() { @tasks.push(makeTask(task)) }
  clear() { @tasks = @undone }
}

view Main {
  @newText = ""

  add() { Tasks.addTask(); @newText = "" }

  <h1>Todo List</h1>
  <div.task repeat={Tasks.tasks}>
    <input type="checkbox" sync={.done} />
  </div>

  <div.toolbar>
    <div.undone> {Tasks.undone.length} tasks left</div>
    <button click={Tasks.clear()}>clear completed</button>
  </div>

  <input enter={add()} placeholder="New Task" />
}