[Caml-list] Functorising over Cohttp's backends

[Dario Teixeira <dario.teixeira@nleyten.com>]

Hi,

Suppose I have a function "make_callback" which creates a callback
ready to be given to Cohttp's Server.make. Here's its signature:

  type callback =
    Cohttp_lwt_unix.Server.IO.conn * Cohttp.Connection.t ->
    Cohttp.Request.t ->
    Cohttp_lwt_body.t ->
    (Cohttp.Response.t * Cohttp_lwt_body.t) Cohttp_lwt_unix.Server.IO.t

  val make_callback: unit -> callback

Note that it's tied to the Lwt+Unix instantiation of Cohttp. Now,
I wish to make it more generic, so it can be used with the Async
backend, for instance.

There's more to it than just using a functor for abstracting over the
IO monad, unfortunately. In particular, the connection type and the
body are also backend-dependent. Anyway, Cohttp's API is notoriously
hard to navigate. Is the generic signature I'm looking for already
defined somewhere, or are the backends so distinct that I might
as well forget about functorising the interface and thus force the
Lwt+Unix backend on my API? (It's the only backend I use myself...)

Thanks in advance!
Best regards,
Dario Teixeira