aztek

import idioms._ // http://github.com/aztek/scala-idioms

trait Cell[T] {
  def ! : T
  def := (value: T) { throw new UnsupportedOperationException }
}

val frp = new Idiom[Cell] {
  def pure[A](a: ⇒ A) = new Cell[A] {
    private var value = a

sadache

Enumeratee.map[Array[Byte]]{ e =>
  val length = e.size
  val CRLF = "\r\n".getBytes("UTF-8")
  (length.toHexString.getBytes ++ CRLF ++ e ++ CRLF):Array[Byte] 
} ><>
Enumeratee.trailing(Seq((0.toHexString.getBytes) ++ (CRLF ++ CRLF)))

sadache

If your csv doesn't contain escaped newlines then it is pretty easy to do a progressive parsing without putting the whole file into memory. The iteratee library comes with a method search inside play.api.libs.iteratee.Parsing :

def search (needle: Array[Byte]): Enumeratee[Array[Byte], MatchInfo[Array[Byte]]]

which will partition your stream into Matched[Array[Byte]] and Unmatched[Array[Byte]]

Then you can combine a first iteratee that takes a header and another that will fold into the umatched results. This should look like the following code:

// break at each match and concat unmatches and drop the last received element (the match)