scala pattern matches

collect pattern matches,

scala> val data = Map((1 -> ("prog" -> "Pink floyd")), (2 -> ("metal" -> "Architects")), (3 -> ("prog" -> "Porcupine Tree")))

data: scala.collection.immutable.Map[Int,(String, String)] = Map(1 -> (prog,Pink floyd), 2 -> (metal,Architects), 3 -> (prog,Porcupine Tree))

scala> data.collect {case (k, v) if v._1 == "prog" => v._2}

res9: scala.collection.immutable.Iterable[String] = List(Pink floyd, Porcupine Tree)

scala> data.collect {case (k, (v1, v2)) if v1 == "prog" => v2}

res10: scala.collection.immutable.Iterable[String] = List(Pink floyd, Porcupine Tree)

scala foldLeft pattern matches,

scala> val data = Map((1 -> ("prog" -> "Pink floyd")), (2 -> ("metal" -> "Architects")), (3 -> ("prog" -> "Porcupine Tree")))

data: scala.collection.immutable.Map[Int,(String, String)] = Map(1 -> (prog,Pink floyd), 2 -> (metal,Architects), 3 -> (prog,Porcupine Tree))

scala> data.foldLeft(""){case (text, (id, (genre, artist))) => text + "\n" + artist}

res17: String =

"

Pink floyd

Architects

Porcupine Tree"