CheckboxError.elm

import Html exposing (..)
import Html.Events exposing (..)
import Html.Attributes exposing (..)
import Html.App as App


main : Program Never
main =
    App.beginnerProgram
        { model = init
        , update = update
        , view = view
        }


type alias Model =
    List Todo


type alias Todo =
    { completed : Bool
    , id : Int
    }



init : Model
init =
    [ Todo False 1
    , Todo False 2
    , Todo False 3
    ]


type Msg
    = SetCompleted Int
    | NoOp


update : Msg -> Model -> Model
update msg model =
    case msg of
        SetCompleted target ->
            let
                updateStatus todo =
                    { todo | completed = target == todo.id }
            in
                model |> List.map updateStatus
        NoOp ->
            model



view : Model -> Html Msg
view model =
    div []
        [ text "Check items 1 or 2, the next item will display checked when it should be unchecked:"
        , div []
            (model
                |> List.filter (Debug.log "todo" >> .completed >> not)
                |> List.map viewItem
            )
        , text <| toString model
        ]



viewItem : Todo -> Html Msg
viewItem todo =
    div []
        [ input
            [ type' "checkbox"
            , checked todo.completed
            , onCheck
                (\on ->
                    if on then
                        SetCompleted todo.id
                    else
                        NoOp
                )
            ]
            []
        , text <| toString todo.id
        ]