parser combinators

addr.json

{
    "address book" : {
        "name" : "John Smith",
        "address" : {
            "street" : "10 Market Street",
            "city" : "San Francisco, CA",
            "zip" : 94111
        },
        "phone numbers" : [
            "408 338-4238",
            "408 111-6892"
        ]
    }
}

JSON.scala

import scala.util.parsing.combinator._

class JSON extends JavaTokenParsers {

  def obj: Parser[Map[String, Any]] = "{" ~> repsep(member, ",") <~ "}" ^^ (Map() ++ _)

  def arr: Parser[List[Any]] = "[" ~> repsep(value, ",") <~ "]"

  def member: Parser[(String, Any)] = stringLiteral ~ ":" ~ value ^^
                                      { case name ~ ":" ~ value => (name, value) }

  def value: Parser[Any] =  obj |
                            arr |
                            stringLiteral |
                            floatingPointNumber ^^ (_.toDouble) |
                            "null" ^^ (_ => null) |
                            "true" ^^ (_ => true) |
                            "false" ^^ (_ => false)
}

ParseJSON.scala

import java.io.FileReader

object ParseJSON extends JSON with App {

  val reader = new FileReader("addr.json")
  println(parseAll(value, reader))

}