Elm message

Component.elm

module Component exposing (..)

import Html exposing (..)
import Html.Events exposing (..)
import Message


type alias Model =
    {}


init : ( Model, Cmd Msg )
init =
    {} ! []


type Msg
    = NoOp
    | SetMessage


update : Msg -> Model -> ( Model, Cmd Msg )
update msg model =
    case msg of
        NoOp ->
            model ! []

        SetMessage ->
            ( model
            , Message.setMessage "Ow yeah!"
                |> Cmd.map (\_ -> NoOp)
            )


view : Model -> Html Msg
view model =
    button [ onClick SetMessage ]
        [ text "Set message" ]

Main.elm

module Main exposing (main)

import Component
import Html exposing (..)
import Html.App as App
import Message


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


type alias Model =
    { message : Message.Model
    , component : Component.Model
    }


init : ( Model, Cmd Msg )
init =
    let
        ( message, messageCmds ) =
            Message.init

        ( component, componentCmds ) =
            Component.init
    in
        { message = message
        , component = component
        }
            ! []


type Msg
    = NoOp
    | ComponentMsg Component.Msg
    | Message Message.Msg


update : Msg -> Model -> ( Model, Cmd Msg )
update msg model =
    let
        _ =
            Debug.log msg msg
    in
        case msg of
            NoOp ->
                model ! []

            ComponentMsg msg' ->
                let
                    ( component, componentCmd ) =
                        Component.update msg' model.component
                in
                    ( { model | component = component }
                    , Cmd.map ComponentMsg componentCmd
                    )

            Message msg' ->
                let
                    ( message, messageCmd ) =
                        Message.update msg' model.message
                in
                    ( { model | message = message }
                    , Cmd.map Message messageCmd
                    )


view : Model -> Html Msg
view model =
    div []
        [ App.map ComponentMsg (Component.view model.component)
        , text model.message
        ]


subscriptions : Model -> Sub Msg
subscriptions model =
    Sub.batch
        [ Sub.map Message (Message.subscriptions model.message)
        ]

Message.elm

module Message exposing (..)

import Task


type alias Model =
    String


init : ( Model, Cmd Msg )
init =
    ( "", Cmd.none )


type Msg
    = NoOp
    | SetMessage String


update : Msg -> Model -> ( Model, Cmd Msg )
update msg model =
    case msg of
        NoOp ->
            model ! []

        SetMessage message ->
            ( message, Cmd.none )


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


setMessage : String -> Cmd Msg
setMessage msg =
    let
        _ =
            Debug.log "received" msg
    in
        Task.perform (\_ -> NoOp)
            (\m -> SetMessage m)
            (Task.succeed msg)

OldMessage.elm

module Message (Model, Action, init, update, actions, clearMessageAddress, clearMessage, setMessage) where

import Effects exposing (Effects)
import Effects.Extra exposing (noFx)
import Html exposing (..)
import Signal
import Time exposing (Time)


-- MODEL


type alias Model =
  { message : Maybe Html
  , timestate : Maybe TimeState
  }


type alias TimeState =
  { elapsedTime : Time
  , prevClock : Time
  }


init : Model
init =
  { message = Nothing
  , timestate = Nothing
  }



-- UPDATE


type Action
  = NoOp
  | SetMessage Html
  | ClearMessage
  | Tick Time


update : Action -> Model -> ( Model, Effects Action )
update action model =
  case action of
    NoOp ->
      model |> noFx

    SetMessage html ->
      ( { message = Just html
        , timestate = Nothing
        }
      , Effects.tick Tick
      )

    Tick time ->
      let
        elapsedTime' =
          case model.timestate of
            Nothing ->
              0

            Just { elapsedTime, prevClock } ->
              elapsedTime + (time - prevClock)
      in
        if elapsedTime' > 5000 then
          ( { message = Nothing, timestate = Nothing }
          , Effects.none
          )
        else
          ( { model
              | timestate =
                  Just
                    { elapsedTime = elapsedTime'
                    , prevClock = time
                    }
            }
          , Effects.tick Tick
          )

    ClearMessage ->
      { message = Nothing, timestate = Nothing } |> noFx



-- SIGNALS


mailbox : Signal.Mailbox Action
mailbox =
  Signal.mailbox NoOp


actions : Signal Action
actions =
  mailbox.signal


clearMessageAddress : Signal.Address ()
clearMessageAddress =
  Signal.forwardTo mailbox.address (\_ -> ClearMessage)


setMessageAddress : Signal.Address Html
setMessageAddress =
  Signal.forwardTo mailbox.address SetMessage


clearMessage : Effects ()
clearMessage =
  Signal.send clearMessageAddress ()
    |> Effects.task


setMessage : Html -> Effects ()
setMessage html =
  Signal.send setMessageAddress html
    |> Effects.task