Discussion on: The basic Elm example that I wish I'd had

[Nimmo]

Slight update: After adding navigation into another application, which meant needing to add a navigation key, I've ended up re-evaluating this at the moment. Although all I've done is added any globally-available info to the model, and kept the state the way I described earlier:

-- MODEL


type alias Model =
    { key : Nav.Key
    , state : State
    }


type State
    = ViewSignUp SignUpData
    | ViewLogin LoginData
    | ViewPasswordReset PasswordResetData
    | Loading

And it's still the state that drives the UI itself:

-- VIEW


view : Model -> Document Msg
view model =
    case model.state of
        Loading ->
            { title = "Some app"
            , body = [ loadingView ]
            }

        ViewSignUp data ->
            let
                signUpView =
                    Html.map (\x -> SignUpMsg x) <| SignUp.view data
            in
            { title = "Sign up to Some app"
            , body = [ signUpView ]
            }

        ViewLogin data ->
            let
                loginView =
                    Html.map (\x -> LoginMsg x) <| Login.view data
            in
            { title = "Log in to Some app"
            , body = [ loginView ]
            }

        ViewPasswordReset data ->
            let
                forgottenPasswordView =
                    Html.map (\x -> PasswordResetMsg x) <| PasswordReset.view data
            in
            { title = "Request a password reset"
            , body = [ forgottenPasswordView ]
            }

[kwitgit]

I do like this better. Somehow it feels a little "forced" to make the model as one giant custom type. With this type of edit, you can still model your door/alarm states elegantly and completely with a big custom type, and get all the benefits of that. But other stuff in the model (like navigation key or login status) that doesn't have anything to do with the door state can live separately, as a different piece of the model record.