nominal flow = ()
nominal phrasing = ()

union child parent =
    | Text :: forall parent. string -> child parent
    | Span :: forall parent. string -> child parent
    | Div :: string -> child flow

union rec children parent =
    | ChildNil :: forall parent. children parent
    | ChildCons :: forall parent. child parent * children parent -> children parent

union element parent =
    | Element :: forall parent. string * children parent -> element parent

inl main () : string =
    inl _ : element phrasing = Element ("p", ChildCons (Div "illegal", ChildNil))
    "unreachable"