run2-python-scala-json-circe

name	run2_python-scala-json-circe
description	Parsing and handling JSON safely in Scala using io.circe

JSON Processing with Circe in Scala

In Python, JSON values are often recursive union types (e.g. str | int | list | dict) parsed dynamically by json.loads. In Scala, recursive sum types for JSON are safely modeled using io.circe.Json (an Algebraic Data Type).

Python

JsonValue = Union[str, int, float, bool, None, list["JsonValue"], dict[str, "JsonValue"]]

def tokenize(self, value: JsonValue) -> Token:
    return Token(json.dumps(value))

Scala (Circe)

import io.circe.Json
import io.circe.syntax._

class JsonTokenizer(val pretty: Boolean = false) {
  def tokenize(value: Json): Token = {
    // Circe handles AST formatting out-of-the-box
    val jsonStr = if (pretty) value.spaces2 else value.noSpaces
    Token(jsonStr, TokenType.STRUCTURED, Map("json" -> true))
  }
}

Safe Tree Traversal

Python often accesses elements via value["key"] or value[idx] which can raise errors. Scala's Circe allows traversing cleanly:

def tokenizePath(value: Json, path: String): Option[Token] = {
  val parts = path.split('.')
  var current: Option[Json] = Some(value)

  for (part <- parts if current.isDefined) {
    val jsonOpt = current.get
    // Safe object access: .asObject and then .flatMap(_(part))
    current = if (jsonOpt.isObject && jsonOpt.asObject.exists(_.contains(part))) {
      jsonOpt.asObject.flatMap(_(part))
    } 
    // Safe array access: .asArray and index bounds checking
    else if (jsonOpt.isArray && part.forall(_.isDigit)) {
      val idx = part.toInt
      val arr = jsonOpt.asArray.get
      if (idx >= 0 && idx < arr.size) Some(arr(idx)) else None
    } else {
      None
    }
  }

  current.map(tokenize)
}

Note: Alternatively, circe's Cursor or optics can be used for deep traversals, but iterating AST options is functionally equivalent to the Python behavior.