extentWith

ExtentWith.elm

extentWith : (a -> a -> Order) -> List a -> Maybe ( a, a )
extentWith toOrder list =
    let
        max a b =
            case toOrder a b of
                GT ->
                    a

                _ ->
                    b

        folder element ( mini, maxi ) =
            case toOrder element mini of
                LT ->
                    -- if new is less than mini, it can never be larger than maxi
                    -- so we're immediately done
                    ( element, maxi )

                EQ ->
                    -- idem
                    ( element, maxi )

                GT ->
                    ( mini, max element maxi )
    in
        case list of
            [] ->
                Nothing

            x :: xs ->
                Just <| List.foldl folder ( x, x ) xs