message wrapping

Foo.elm

module Foo exposing (..)


type Msg
    = Uno
    | Dos
    | Tres


update msg foo =
    case msg of
        Uno ->
            1

        Dos ->
            2

        Tres ->
            3

Main.elm

module Main exposing (..)

import Html exposing (..)
import Html.Attributes exposing (..)
import Html.Events exposing (..)
import Foo


type alias Model =
    { foo : Int
    , bar : Int
    }


type Msg
    = Bar
    | FooMsg Foo.Msg


update : Msg -> Model -> Model
update msg model =
    case msg of
        FooMsg msg ->
            { model | foo = Foo.update msg model.foo }

        Bar ->
            { model | bar = 34 }


view : Model -> Html Msg
view model =
    section []
        [ text <| toString model
        , button [ onClick (FooMsg Foo.Uno) ] [ text "Foo.Uno" ]
        , button [ onClick (FooMsg Foo.Dos) ] [ text "Foo.Dos" ]
        , button [ onClick Bar ] [ text "Bar" ]
        ]


main : Program Never Model Msg
main =
    beginnerProgram
        { update = update
        , view = view
        , model = { foo = 0, bar = 0 }
        }