FreekLog.scala

package stripes


import cats.free.Free
import cats.~>


import freek._


object Log {


  sealed trait LogLevel
  case object ErrorLevel extends LogLevel
  case object WarnLevel extends LogLevel
  case object InfoLevel extends LogLevel
  case object DebugLevel extends LogLevel

  trait DSL[A]
  case class LogMsg(level: LogLevel, msg: String) extends DSL[Unit]

  /** just helpers without any weird implicits */
  def debug(msg: String) = LogMsg(DebugLevel, msg)
  def info(msg: String) = LogMsg(InfoLevel, msg)
}


object Logger extends (Log.DSL ~> cats.Id) {
  def apply[A](a: Log.DSL[A]) = a match {
    case Log.LogMsg(lvl, msg) =>
      println(s"$lvl $msg")
  }
}

object Program {


  type PRG =  Log.DSL :|: NilDSL

  val PRG = DSL.Make[PRG]


  def prog : Free[PRG.Cop, Unit] = for {
    _ <- Log.debug("This is a debug").freek[PRG]
  } yield ()



  val interpreter = Logger


  def main(args: Array[String]): Unit = {
    // println(prog.interpret(interpreter))

  }
}