BufferedReaderをIterateeで扱う

App.scala

import java.io.{ BufferedReader, FileReader }

import scalaz._, Scalaz._
import scalaz.effects._
import IterV._

object App {
  def main(args: Array[String]) {
    val br = new BufferedReader(new FileReader("test2.txt"))
    val io = byEnumerator(br)
    io.unsafePerformIO
  }

  def byEnumerator(br: BufferedReader): IO[Unit] = {
    val lineIter: IterV[String, Int] = head[String] map {
      lineOpt => (lineOpt map (_.length)) | 0
    }
    val iter: IterV[String, Stream[Int]] = repeat[String, Int, Stream](lineIter)
    val enumerator: EnumeratorM[IO, String] = getReaderLines(br)
    val read: IO[Int] = enumerator(iter) map { iter =>
      iter.run reduce (_ + _)
    }
    read map (_.toString) flatMap (putStrLn _)
  }
}