PhoneBook

import scala.io.Source

object Phonebook extends App {

  type ??? = Nothing

  //a nice alias for the tuple type representing one entry in the phonebook
  type PhonebookEntry = Tuple5[String, String, String, String, String]
  //another alias for the actual phonebook
  type Phonebook = List[PhonebookEntry]

  val regex = """^(0\d+) (\d+) (\w.+?), (.+), (.+)$""".r

  def line2Book(line:String, book:Phonebook) = line match {
    case regex(area,number,name,street,city) => (area,number,name,street,city) :: book
    case _ => book
  }

  //This function reads the given file and returns a list of entries (=tuples)
  def fileToPhoneBook(filename: String):Phonebook =
    Source.fromFile(filename).getLines().foldRight[Phonebook](Nil)(line2Book)

  //Read the file
  val phoneBook = fileToPhoneBook("./src/files/phonebook.txt")

  //print all entries in the phonebook
  phoneBook foreach println

  //This function returns a list containing all names of people living in the specified city
  def peopleLivingIn(book: Phonebook, city:String) =
    //book.filter(entry => entry._5 == city)
    book.filter(_._5 == city)

  println("People living in Graz")
  peopleLivingIn(phoneBook, "Graz") foreach println

}