This defines a superset of JSON, with the addition of "variables" which appear between curly braces (e.g. {{someVariable}}). The format of the variables can be customized by the user, although by default it will parse an alphanuxmeric identifier which can start with a letter or underscore and subsequently contain any letter, digit or _. Although by default variables are strings, the vjson type is polymorphic and the structure can be mapped over to support more complex information.

{
  "id": {{id}},
  "color": {{color}},
  "allSizes": ["small", "medium", "large"],
  "size": {{size}},
}

This library provides tools for:

• Parsing the above syntax, including custom variable formats
• Finding the set of variables in a given tree
• Replacing all of the variables in a tree with JSON, producing a JSON object

let vJson: VJson.t(string) = VJson.parseDefault("{
  \"id\": {{id}},
  \"color\": {{color}},
  \"allSizes\": [\"small\", \"medium\", \"large\"],
  \"size\": {{size}},
}")->Belt.Result.getExn;

// Prints "Set { 'id', 'color', 'size' }"
Js.log(vJson->VJson.findVariables);

// Customizing the variable format to integers
let vJsonWithInts: VJson.t(int) = VJson.(
    "{{123}}"
    |> VJson.parseWithRegex([%re {|/\d+/|}])
    |> Belt.Result.getExn
  )
  ->VJson.map(int_of_string)

yarn re:build

yarn re:watch