(Program
  (Module
    (Identifier))
  (Function
    (Identifier)
    (Args)
    (Other "type_declaration"
      (TypeDecl
        (Identifier)
        (StructTy
          (FieldDecl
          { (Identifier)
          ->(Identifier) }
          { (Identifier)
          ->(Identifier) }
          {+(Identifier)+}))))))