Return F# list as web result

RestServer.fs

type KeyValues = Map<string,string>

type DataList = {
    Articles: KeyValues list option
}

let dataList : DataList = {
    Articles = Option.None
}

let deliverList (list: KeyValues list option) (listName: string) =
    let values = match list with
        | None -> ReadDataFile listName
        | Some data -> data
    let answer = JsonSerializer.Serialize values
    answer |> text
    
let deliverData listName =
    match listName with
    | "articles" ->
        deliverList dataList.Articles "articles" 
    | _ -> setStatusCode 404 >=> text $"{listName} not Found" ]

let webApp =
    choose [
        GET >=>
            choose [
                routef "/data/%s" deliverData
            ]
        setStatusCode 404 >=> text "Not Found" ]