Make ppx inline Ppx_deriving_router_runtime

[davesnx]

The ppx could generate the full module binding on each case (even when json decoding is used) and avoid users to open the runtime, which is expected to be there in the first place.

module Api = struct
-  open Ppx_deriving_router_runtime.Primitives
-  open Ppx_deriving_json_runtime.Primitives

  type user = { id : int } [@@deriving json]

  type _ t =
    | List_users : user list t [@GET "/"]
    | Create_user : user t [@POST "/"]
    | Get_user : { id : int } -> user t [@GET "/:id"]
    | Raw : Ppx_deriving_router_runtime.response t [@GET "/raw"]
  [@@deriving router]
end

[andreypopp]

The open Ppx_deriving_router_runtime.Primitives is needed because ppx cannot know if types like string, _ list or other are the ones from Stdlib or user-defined.

If we make it generate fully qualified names with Primitives in it, then this code would not work:

type string = ...

let x = {a : string} [@@deriving json]

[davesnx]

but that's a good tradeoff, no? If you define your own primitive types... it will def break

[andreypopp]

but that's a good tradeoff, no? If you define your own primitive types... it will def break

it won't break if you define/derive to_json/of_json, it'll shadow Primitives

[davesnx]

But why would you define a string type and string_to_json/string_of_json?

[davesnx]

Similar concept/tradeoff from melange-json ppx: melange-community/melange-json#19