Deserialise YAML Data using hl_yaml
Task
Data Formats / YAML / Deserialise YAML Data
Opam Packages Used
- hl_yaml Tested with version: 1.0.0 — Used libraries: hl_yaml
- ppx_deriving_yojson Tested with version: 3.7.0 — Used libraries: ppx_deriving_yojson
Code
This is the string we are deserializing into the types we define below.
let yaml = {|
french name: pâte sucrée
ingredients:
- name: flour
weight: 250
- name: butter
weight: 100
- name: sugar
weight: 100
- name: egg
weight: 50
- name: salt
weight: 5
steps:
- soften butter
- add sugar
- add egg and salt
- add flour
|}
The [@@deriving of_yojson] attribute makes the ppx from the library ppx_deriving_yojson generate the function
ingredient_of_yojson : Yojson.Safe.t -> (ingredient, string) result.
If both serialising and deserialising are needed, replace of_yojson by yojson.
type ingredient = {
name: string;
weight: int;
} [@@deriving of_yojson]
The function recipe_of_yojson : Yojson.Safe.t -> (ingredient, string) result generated here internally uses
ingredient_of_yojson.
type recipe = {
name: string; [@key "french name"]
ingredients: ingredient list;
steps: string list;
} [@@deriving of_yojson]
parse takes a function that converts from Yojson.Safe.t into the desired record type as an argument.
let pate_sucree =
yaml
|> Hl_yaml.Unix.parse ~of_yojson:recipe_of_yojson