A minimal example of how to use ocaml-webmachine to build a REST API. This API returns HTTP error 406 ("Not Acceptable") for every valid request

minimal-webmachine-example.ml

(** Returns http error 406 for every valid request.
    build with: `ocamlbuild -use-ocamlfind -pkgs cohttp.lwt,lwt,webmachine main.byte` *)
open Cohttp
open Cohttp_lwt_unix
open Lwt.Infix

module Wm = struct
    include Webmachine.Make(Cohttp_lwt_unix_io)
    module Rd = Webmachine.Rd
end

class handler = object(self)
    inherit [Cohttp_lwt_body.t] Wm.resource

    method content_types_accepted rd = Wm.continue [] rd
    method content_types_provided rd = Wm.continue [] rd
end

let main () =
    let routes = [
        ("/foo", fun () -> new handler);
        ("/bar/:id", fun() -> new handler);
    ] in
    let callback _conn request body =
        Wm.dispatch' routes body request >|= (function
          | Some r -> r
          | None -> (`Not_found, Header.init (), `String "Nope sorry", []))
        >>= (fun (status, headers, body, path) ->
        Server.respond ~status ~headers ~body ()) in
    Server.create ~mode:(`TCP (`Port 8081)) (Server.make ~callback ())

let () = Lwt_main.run(main ())