Suggestion: Add rules json schema about markdownlint

[DavidAnson]

I created that schema because the VS Code extension vscode-markdownlint can use it to provide syntax highlighting in the editor (i.e., warning). How are you thinking to use the schema with markdownlint? Would you want to throw an exception if the user provides a config that isn't valid? My worry about that would be that it is too restrictive (i.e., error). For example, note that I use the unsupported comment key to add information to the sample styles: https://github.com/DavidAnson/markdownlint/blob/master/style/relaxed.json

I don't think I would want to block a valid user just because they had extra content in their JSON.

[mizunashi-mana]

For example, note that I use the unsupported comment key to add information to the sample styles: https://github.com/DavidAnson/markdownlint/blob/master/style/relaxed.json

In this case, json schema permits additional properties on default. So, this is not problem.
However, there might be problems in other cases.

Yet, I think the rules structure of markdownlint are more complexity than other linter config.
For markdownlint developers, we should provide validations.
json-schema is flexible and has many supports. For example, we can nest such as:

{
  "type": "object",
  "properties": {
     "rules": {
         "$ref": "rules.schema.json"
     }
  }
}

ref: https://spacetelescope.github.io/understanding-json-schema/structuring.html

And, related writers can choose best library that suits them from many libraries.

• https://github.com/geraintluff/tv4
• https://github.com/epoberezkin/ajv
• https://github.com/tdegrunt/jsonschema
• etc.

I think providing json schema, providing cost saving and flexible validations for markdownlint tool writers.

[DavidAnson]

I think this could work as a new validateSchema option - if true, an exception is thrown for an invalid schema. I use tv4 in vscode-markdownlint, so it would be fairly straightforward to add.

However, I'm reluctant to introduce a new dependencies for something non-essential like this. :( (There's currently just one and it's the Markdown parser!) I'd worry less about using devDependencies, but I'm not sure that works for the scenario you have in mind.

I may need to think about this more.