this isn't the most basic. as it is showing how to use commands in the update function, and thus can't be used with HTML.beginnerProgram. this is an extension from the egghead todo list tutorial

basic todo list.elm

import Html exposing (..)
import Html.Attributes exposing (..)
import Html.App as Html
import Html.Events exposing (onInput, onClick)
import String exposing (..)
import Random exposing (..)

main = 
  Html.program
  {
    init = init,
    update = update,
    view = view,
    subscriptions = subscriptions
  }


-- SUBSCRIPTIONS


subscriptions : Model -> Sub Msg
subscriptions model =
  Sub.none


type alias Model =
  { 
  newLabel: String,
  todos: List TodoItem
  }
  
type alias TodoItem =
  {
    id: Int,
    label: String
  }
  
model = { 
  newLabel = "", 
  todos = []
  }
  
init = (model, Cmd.none)

type Msg = 
    UpdateText String 
  | AddItem Int
  | AddNewItem
  | RemoveItem Int
  
todoIdGenerator =
   Random.int 0 maxInt


update msg model = 
  case msg of
  
    UpdateText text ->
      ({ model | newLabel = text }, Cmd.none)
      
    --this is just to generate the id for the list item...
    AddNewItem ->
      (model, Random.generate AddItem todoIdGenerator)
      
    AddItem id ->
      ({ model | todos = {
          label = model.newLabel, 
          id = id
        } :: model.todos 
      }, Cmd.none)
      
    RemoveItem idToRemove -> 
      ({ 
        model | 
          todos = 
            List.filter (\{id} -> id /=  idToRemove ) model.todos 
      }, Cmd.none)

todoItem todo = 
  li []
    [
    div [] [
      text ((toString todo.id) ++ " " ++ todo.label),
      --This maybe should be handled in the removeItem update case
      button [ onClick (RemoveItem todo.id) ] [ text "X" ]
     ]]

todoList todos =
  ul [] (List.map todoItem todos)

view model = 
  div [] 
  [ 
    input [ type' "text", 
            onInput UpdateText, 
            value model.newLabel
          ] [], 
    button [ onClick AddNewItem ] [ text "add todo" ],
    todoList model.todos
  ]