(docs) Cookbooks "Serialise JSON Data using ppx_yojson_conv" and "Deserialise JSON Data using ppx_yojson_conv"

data/cookbook/deserialise-from-json/00-ppx_yojson_conv.ml

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+---
+packages: 
+- name: ppx_yojson_conv
+  tested_version: "v0.17.0"
+  used_libraries:
+  - ppx_yojson_conv
+- name: yojson
+  tested_version: 2.1.2
+  used_libraries:
+  - yojson
+---
+(* We open `Ppx_yojson_conv_lib.Yojson_conv.Primitives` to bring the functions that deserialise primitive types in scope. *)
+open Ppx_yojson_conv_lib.Yojson_conv.Primitives
+
+let json = {|
+{
+  "name": "ocaml",
+  "url": "https://ocaml.org/"
+}
+|}
+
+(* The annotation `[@@deriving of_yojson]` causes the PPX from `ppx_yojson_conv` to generate a function
+  `language_of_yojson` that converts values from type `Yojson.Safe.t` to `language`. *)
+type language = { 
+  name: string; 
+  url: string 
+} [@@deriving of_yojson]
+
+(* First we convert the JSON string to `Yojson.Safe.t` and then we use the generated function to create the record.
+   If parsing fails, an `Of_yojson_error` exception is thrown that we can handle. *)
+try
+  let result = 
+    json
+    |> Yojson.Safe.from_string 
+    |> language_of_yojson 
+  Some result
+with Ppx_yojson_conv_lib.Yojson_conv.Of_yojson_error (exception, _) ->
+  let _ = 
+    Printexc.to_string exception print_endline in
+  None

data/cookbook/serialise-to-json/00-ppx_yojson_conv.ml

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+---
+packages: 
+- name: ppx_yojson_conv
+  tested_version: "v0.17.0"
+  used_libraries:
+  - ppx_yojson_conv
+- name: yojson
+  tested_version: 2.1.2
+  used_libraries:
+  - yojson
+---
+(* `Ppx_yojson_conv_lib.Yojson_conv.Primitives` contains functions needed to serialise values of primitive types. *)
+open Ppx_yojson_conv_lib.Yojson_conv.Primitives
+
+(* The annotation `[@@deriving to_yojson]` causes the PPX from `ppx_yojson_conv` to generate a function
+  `yojson_of_language` that converts values from type `language` to `Yojson.Safe.t`. *)
+type language = { 
+  name: string; 
+  url: string 
+} [@@deriving to_yojson]
+
+let ocaml_language = { 
+  name: "ocaml"; 
+  url: "https://ocaml.org/" 
+}
+
+(* We convert the value `ocaml_language` to a `Yojson.Safe.t`, using the function `yojson_of_language` generated by the PPX,
+   and then convert that to a string. *)
+let () = 
+  ocaml_language
+  |> yojson_of_language 
+  |> Yojson.Safe.to_string 
+  |> print_endline