scala3_given_instances.scala

import java.util.{Date as JDate}
import scala.io.Source as S

trait JsonOps[T] {
  def stringify(t: T): String

  extension (x:T) def toJSON(): String = stringify(x)
}

given intJsonOps: JsonOps[Int] with {
  override def stringify(t: Int): String = t.toString
}

given stringJsonOps: JsonOps[String] with {
  override def stringify(t: String): String = "\"" + t + "\""
}

given listJsonOps[T](using j: JsonOps[T]): JsonOps[List[T]] with {
  override def stringify(t: List[T]): String = {
    val s = StringBuilder()
    s.append("[")
    t.foreach(it => s.append(j.stringify(it)).append(","))
    s.append("]")
    s.toString
  }
}

def toJson[T](t: T)(using j: JsonOps[T]) = j.stringify(t)


object A {
  extension[T] (t: T)
    def toJson()(using j: JsonOps[T]): String = j.stringify(t)
}

trait X[T]{
  extension (t:T) def x(): String
}

given intX: X[Int] with {
  extension (t: Int) def x(): String = t.toString()
}

object Main {
  def main(args: Array[String]): Unit = {
    println("Hello world!")
    println(msg)

    val s = S.fromFile("build.sbt").getLines().mkString(",\n")
    //println(s)
    println(JDate())

    println(toJson(100))
    println(toJson("200"))

    println(toJson(List(1, 2, 3)))
    println(toJson(List("a", "b", "c")))

    println(List(1, 2, 3).toJSON())

    {
      import A.*
      println("hello".toJson())

      println(List("e", "f").toJson())
    }
    
    {
      import intX.*
      println(100000.x())
    }
  }

  def msg = "I was compiled by dotty :)"
}