totally non-complex way to list files in a directory

gistfile1.scala

val openFile: String => IO[File]
  = path => io { new File(path) }

val fileName: File => String
  = _.toString

val putStrLn: String => IO[Unit]
  = s => io { println(s) }

val listFiles: File => IO[Seq[File]]
  = f => io { f.listFiles }

val result = openFile(".") >>= listFiles >>= (_ traverse_ (fileName map putStrLn))

result.unsafePerformIO