trading_model.eliom:
[%%shared
type sellOrderCapture = {
  sellOrderId : int;
}
[@@deriving yojson]

type buyOrderCapture = {
  buyOrderId : int;
  quantity : int;
}
[@@deriving yojson]

type t = {
  sellOrder : sellOrderCapture;
  buyOrders : buyOrderCapture list;
}
[@@deriving yojson]

trading_model.type_mli:

module MatchCapture :
sig
  type sellOrderCapture = { sellOrderId : int; }
  val sellOrderCapture_to_yojson : sellOrderCapture -> Yojson.Safe.t
  val sellOrderCapture_of_yojson :
    Yojson.Safe.t -> sellOrderCapture Ppx_deriving_yojson_runtime.error_or
  type buyOrderCapture = { buyOrderId : int; quantity : int; }
  val buyOrderCapture_to_yojson : buyOrderCapture -> Yojson.Safe.t
  val buyOrderCapture_of_yojson :
    Yojson.Safe.t -> buyOrderCapture Ppx_deriving_yojson_runtime.error_or
  type t = {
    sellOrder : sellOrderCapture;
    buyOrders : buyOrderCapture list;
  }
  val to_yojson : t -> Yojson.Safe.t
  val of_yojson : Yojson.Safe.t -> t Ppx_deriving_yojson_runtime.error_or
  val _ : Yojson.Safe.t -> t Ppx_deriving_yojson_runtime.error_or
end