svcc2013-JSONRExample.scala

//the class into which we want to decode some JSON
//the JSON looks like this: {"one": 1, "two": 2}
case class MyClass(one: Int, two: String)

val MyClassJSONR: JSONR[MyClass] = new JSONR[MyClass] {
  //the method that transforms some JSON into a Result
  //Result is either a Failure (instead of throwing an exception) or Success
  override def read(json: JValue): Result[MyClass] = {
    val fieldOne: Result[Int] = field[Int]("one")(json)
    val fieldTwo: Result[Int] = field[Int]("two")(json)
    for {
      one <- fieldOne
      two <- fieldTwo
    } yield {
      MyClass(one, two)
    }
}

val myClassResult: Result[MyClass] = fromJSON[MyClass](someJSON)(MyClassJSONR)

//myClassResult is either:
// - a Failure describing why we couldn't decode the JSON
// - a Success with the MyClass instance in it
//type safety rules!