Main.elm

import Html exposing (..)
import Html.Attributes exposing (..)
import Html.Events exposing (..)
import Html.App exposing (..)
import Json.Decode exposing (..)

import Http
import Task

type alias Todo =
  { id : Int
  , text : String
  , done : Bool }

type alias Model =
  List Todo

type Msg =
  Check Int

update : Msg -> Model -> Model
update msg model =
  case msg of
    Check id ->
      let
        update todo =
          if todo.id /= id then todo else { todo | done = not todo.done }
      in
        List.map update (Debug.log "model" model)
        

view : Model -> Html Msg
view model =
  model |> List.map (renderTodo Check) |> div []

renderTodo : (Int -> Msg) -> Todo -> Html Msg
renderTodo msg todo =
  div []
    [ label []
      [ text todo.text
      , input [ type' "checkbox", onClick (msg todo.id) ] [] ] ]

main = beginnerProgram
  { model = List.map (\i -> Todo i (toString i) False) [1..10000]
  , update = update
  , view = view }