OCaml - How to serialize and deserialize Yaml to records - yaml

Question

What are the current community preferred libraries to parse and work with YAML and how do you use them to serialize and deserialize a record like this:
type book = {
title: string;
authors: string list
}

Answer 1

This is how I got string -> record and back.
$ opam update
$ opam install yaml ppx_deriving_yaml
Update dune with the preprocess clause:
; `dune` file
(executable
(name main)
(libraries yaml)
(preprocess
(pps ppx_deriving_yaml)))
Short version:
let serialize_book (book_rec : book) : (string, string) result =
let res = Yaml.to_string (book_to_yaml book_rec) in
map_error ~f:(fun (`Msg m) -> m) res
let deserialize_book (book_str : string) : (book, string) result =
let res =
Yaml.of_string book_str >>= fun yaml_value -> book_of_yaml yaml_value
in
map_error ~f:(fun (`Msg m) -> m) res
More verbose/descriptive version:
(* Define a record *)
(* `[##deriving yaml]` generates a bunch of functions, one being `book_to_yaml` to convert the record into a Yaml type, another `book_of_yaml` to convert Yaml type to record *)
type book = {
title: string;
authors: string list
} [##deriving yaml]
let serialize =
let (v: book) = { title = "Cryptonomicon"; authors = [ "Neal Stephenson" ] } in
(* `book_to_yaml` converts from record to `yaml res` where res is a Result *)
let yaml_structure = book_to_yaml v in
(* `to_string` converts from a `yaml` type'ed data structure to string *)
match Yaml.to_string yaml_structure with
| Ok s ->
print_endline ("Serialize:");
print_endline (s)
| Error (`Msg e) -> print_endline e
let deserialize =
let str = "title: Cryptonomicon\nauthors:\n- Neal Stephenson" in
(* `of_string converts from string to a `yaml res` data structure, where `res` is Result *)
match Yaml.of_string str with
| Ok yaml_value ->
(* `book_of_yaml` is generated by `[##deriving yaml]` *)
(* `book_of_yaml` converts from `yaml` type to `book res` where res is Result *)
(match book_of_yaml yaml_value with
| Ok t ->
print_endline ("Deserialize:");
print_endline ("Title: " ^ t.title);
print_endline ("Authors: " ^ String.concat ", " t.authors);
| Error `Msg e -> print_endline ("Error - convert to book: " ^ e))
| Error `Msg e -> print_endline ("Error - parsing: " ^ e)