FileReader.scala

import java.io._
import monix.reactive.Observable

object FileReader {
  def fileObservable(files: Seq[String]): Observable[String] = {
    Observable.fromIterable(files).flatMap({ file =>
      Observable.fromLinesReader(new BufferedReader(new InputStreamReader(new FileInputStream(file))))     
      .doOnSubscribe(() => println(s"START [$file]"))
      .doOnComplete(() => println(s"FINISH [$file]"))
    })
  }
}