]> Hi, > So my question is how can I make the Foobar code behave as if it were > defined inside Node. Based on a previous thread [1], I'm guessing there > is a solution, but I've been unable to hit on its exact formulation. There have been no replies yet to my question, but I'm still stuck with this little problem. The offending code is below; though it doesn't compile, I reckon that all it needs is a suitable type annotation. I'm guessing this because the function capitalise_node function will compile fine if placed inside the Node module. Any ideas on how to solve this? Thanks in advance! Best regards, Dario Teixeira module Node: sig type node_t = private | Text of string | Bold of node_t list | Href of string | Mref of string * node_t list type +'a t = private node_t val text: string -> [> `Nonlink ] t val bold: 'a t list -> 'a t val href: string -> [> `Link ] t val mref: string -> [< `Nonlink ] t list -> [> `Link ] t end = struct type node_t = | Text of string | Bold of node_t list | Href of string | Mref of string * node_t list type +'a t = node_t let text txt = Text txt let bold seq = Bold seq let href lnk = Href lnk let mref lnk seq = Mref (lnk, seq) end module Foobar: sig open Node val capitalise_node: 'a t -> 'a t end = struct open Node let capitalise_node node = let rec capitalise_node_aux forbid_link node = match (forbid_link, node) with | (_, Text txt) -> text (String.capitalize txt) | (x, Bold seq) -> bold (List.map (capitalise_node_aux x) seq) | (false, Href lnk) -> href lnk | (false, Mref (lnk, seq)) -> mref lnk (List.map (capitalise_node_aux true) seq) | _ -> failwith "oops" in capitalise_node_aux false node end