Figuring out how to model and walk recursive relationships in Elm

recursive-walking.elm

type alias Content =
    { title : String
    , copy : String
    , children : Children
    }


type Children
    = Children (List Content)



tableOfContents : List ( String, String ) -> Model -> Html Msg
tableOfContents parentStyles { document } =
    let
        renderHeading { title, children } =
            li []
                [ text title
                , ul [] (walkChildren children)
                ]

        walkChildren (Children children) =
            List.map renderHeading children
    in
        renderHeading document