pub(all) struct Frontmatter {
  title : String?
  description : String?
  layout : String?
  sidebar : Bool
  outline : OutlineConfig?
  islands : Array[String]
  prev : NavLink?
  next : NavLink?
  image : String?
  og_type : String?
  twitter_card : String?
  ssr : Bool
  renderer : String?
  noindex : Bool
  revalidate : Int?
  date : String?
  author : String?
  tags : Array[String]
  draft : Bool
  featured : Bool
  cover_image : String?
}

pub(all) struct NavLink {
  text : String
  link : String
} derive(ToJson, 
@moonbitlang/core/json.FromJson
FromJson)

pub(all) struct OutlineConfig {
  level_min : Int
  level_max : Int
} derive(ToJson, 
@moonbitlang/core/json.FromJson
FromJson)

fn from_cst(fm : 
@mizchi/markdown.Frontmatter
Frontmatter) -> Frontmatter