ppx.ml

module User = struct
  type t = [ `user of string ]
  let t user = `user "teej_dv"
  
  let get (l : [> t ] list) : string =
    Core.List.find_map l ~f:(function
      | `user s -> Some s
      | _ -> None)
    |> Core.Option.value_exn
  ;;

end

(* would be written like, i think you can actually generate from this haha, but i would have to check *)
module%context User = [`user of string]

module Log = struct
  type t = [ `log of string -> unit ]
  let t log = `log print_endline
end

(* this is the expanded result *)
let ctx : [ User.t | Log.t ] list = [ User.t "teej_dv"; Log.t print_endline ]

(* with ppx, not yet written *)
let%context ctx = [ User.t "teej_dv"; Log.t print_endline ]