file parse example with scalaz-stream

gistfile1.scala

import scalaz._
import scalaz.stream.Process._
import scalaz.stream.Process
import scalaz.stream.io
import scalaz.stream.process1
import scala.util.matching.Regex


def matchRegex(pattern:Regex) : Process1[String,String] = 
 receive1[String,String]({
   case s@pattern(_) => emit(s)
   case s => Halt(new Exception(s"Failed to parse $s, does not match regex: $pattern"))
   })
   
val trailer = "|TRAILER|(\\n+)".r   
   
val lineOrTerm : Process1[String,String]  = {
 def go(lines:Int) =
  matchRegex("(\\|[^\\|]*)+".r).flatMap {
   case trailer(count) if count.toInt == lines => halt
   case trailer(count) => Halt(new Exception(s"Expected $count lines, but got $lines"))
   case s => emit(\/-(s)) fby go(lines+1)
  }
  go(0)
}


val source = 
  io.linesR("/some/file.txt" |>
  buffer(buffersize) |>
  (matchRegex("HEADER.*".r) fby matchRegex("(\\|[^\\|]*)+".r) fby lineOrTerm) |>
  process1.utf8Encode 

(source to io.fileChunkW("target/file.dat")).run.run