scalaz Iterateeでファイルを読み込む練習

Practice1.scala

package iteratee.practice

import scalaz._
import Scalaz._
import effects._
import java.io.File

/**
 * http://code.google.com/codejam/contest/1343486/dashboard
 * の問題ファイルを読み込んでみる練習
 */
object Practice1 extends App {
  case class Problem(n: Int, k: Int)

  lazy val probRegex = """^(\d+) +(\d+)$""".r

  def line2Prob: String => Option[Problem] = {
    case probRegex(n, k) => (for {
      ni <- n.parseInt
      ki <- k.parseInt
    } yield Problem(ni, ki)).toOption
    case _ => None
  }

  def headProb = IterV.head[String] map (_ >>= line2Prob)
  def repeatProb = IterV.repeat[String, Option[Problem], List](headProb) map (_.flatten)
  def readProb = IterV.drop(1) >>=| repeatProb

  val f = new File("practice/1-2.in");
  val lines = getFileLines(f)
  val io = lines(readProb) >>= { iterv =>
    val itervio = iterv.run map (p => putStrLn(p.toString))
    itervio.sequence[IO, Unit] map (_ => ())
  }
  io.unsafePerformIO
}