ReaderをIterateeで扱う

App.scala

import java.io.{ Reader, FileReader }

import scalaz._, Scalaz._
import effect._, IO._
import iteratee._, Iteratee._

object App extends SafeApp{
  val separator = sys.props("line.separator").head

  override def run(args: ImmutableArray[String]): IO[Unit] = {
    val r = new FileReader("test2.txt")
    byEnumerator(r)
  }

  type IEOC = IoExceptionOr[Char]

  def byEnumerator(r: Reader): IO[Unit] = {
    val lineIter = takeWhile[IEOC, Stream](_ map (_ =/= separator) valueOr false) map (_.length)
    val iter = repeatBuild[IEOC, Int, Stream](lineIter).up[IO] map (_.sum)
    val enum = enumReader(r)
    val read = iter &= enum
    (read.run >>= putOut) >> putStrLn("")
  }
}