ocamlppx

Are there any usage examples for the OCaml ppx_xml_conv module

I'm looking for a simple example for the ppx_xml_conv module from janestreet. I'm not terribly familiar with the (relatively) new ppx thing and can't really figure it out from the source code. Ultimately, I'm trying to write a client for an old SOAP service, and want to turn the xsd (from the wsdl) into a type and serializer/deserializer.

Solution

  • Since there is a bug in ppx_xml_conv, I'll give an example for ppx_sexp_conv which works identically.

    $ cat a.ml
open Sexplib.Std

type attr = {
  attr_id : string;
  attr_path : string;
  attr_value : string;
} [@@deriving sexp]

$ cat a.mli
type attr = {
  attr_id : string;
  attr_path : string;
  attr_value : string;
} [@@deriving sexp]

$ ocamlfind ocamlc -package sexplib,ppx_sexp_conv -dsource -c a.mli
type attr = {
  attr_id: string;
  attr_path: string;
  attr_value: string;}[@@deriving sexp]
val attr_of_sexp : Sexplib.Sexp.t -> attr
val sexp_of_attr : attr -> Sexplib.Sexp.t

$ ocamlfind ocamlc -package sexplib,ppx_sexp_conv -dsource -c a.ml
(* ... long output ... *)

    I used the -dsource flag so you can see the generated output. Note that it wasn't necessary to create a ppx executable and call it separately. Compiling with the ppx_sexp_conv package causes that package's ppx extension to automatically get applied.

    As another example here's an executable:

    $ cat b.ml
open Sexplib.Std

type attr = {
  attr_id : string;
  attr_path : string;
  attr_value : string;
} [@@deriving sexp]

let x = {attr_id="abc"; attr_path="foo/bar"; attr_value="something"}

let () = Printf.printf "sexp: %s\n" (Sexplib.Sexp.to_string (sexp_of_attr x))

$ ocamlfind ocamlc -package sexplib,ppx_sexp_conv -linkpkg b.ml

$ ./a.out 
sexp: ((attr_id abc)(attr_path foo/bar)(attr_value something))