modes.scala

package sudoku.errors

import scala.language.higherKinds
import scala.reflect.ClassTag

object Modes {
  trait Mode {
    type Result[_, _]

    def run[E : ClassTag, A](a: => A): Result[E, A]
  }

  object Mode {
    implicit val exceptionsMode = new Mode {
      type Result[E, A] = A

      def run[E : ClassTag, A](a: => A): A = a
    }

    implicit val optionMode = new Mode {
      type Result[E, A] = Option[A]

      def run[E : ClassTag, A](a: => A): Option[A] = {
        try {
          Some(a)
        } catch {
          case _: E => None
        }
      }
    }

    implicit val eitherMode = new Mode {
      type Result[E, A] = Either[E, A]

      def run[E : ClassTag, A](a: => A): Either[E, A] = {
        try {
          Right(a)
        } catch {
          case ex: E => Left(ex)
        }
      }
    }
  }
}

object Runner {
  import Modes._

  def parseInt(s: String)(implicit mode: Mode): mode.Result[NumberFormatException, Int] = {
    mode.run {
      s.toInt
    }
  }
}