The code I rewrite all the time to make a single page web application in Elm

Main.elm

module Main exposing (..)

import Browser exposing (Document, UrlRequest)
import Browser.Navigation exposing (Key)
import Url exposing (Url)

type alias Flags = ()
type alias Model = ()
type alias Msg = ()

main : Program Flags Model Msg
main =
    Browser.application
        { init = init
        , onUrlChange = onUrlChange
        , onUrlRequest = onUrlRequest
        , subscriptions = subscriptions
        , update = update
        , view = view
        }

init : Flags -> Url -> Key -> (Model, Cmd Msg)
init _ _ _ =
    ((), Cmd.none)

onUrlChange : Url -> Msg
onUrlChange _ =
    ()

onUrlRequest : UrlRequest -> Msg
onUrlRequest _ =
    ()

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

update : Msg -> Model -> (Model, Cmd Msg)
update _ model =
    (model, Cmd.none)

view : Model -> Document Msg
view _ =
    { title = ""
    , body = []
    }