//
// program to track bank balance
// prompts for initial balance, 
// then 'c' for credit, 'd' for debit, 'q' for quit
//

def transaction(bal : Int) {
  println("balance "+bal)
  println("what do you want to do?")
  println("c for credit, d for debit, q for quit")
  val what = readChar
  if (what == 'q') {
    println("done!")
  }
  else if ((what == 'c') || (what == 'd')) {
    println("amount?")
    val amt = readInt
    val newBalance = if (what == 'c') (bal + amt) else (bal - amt)
    transaction(newBalance)
  }
  else {
    println("mistake!")
    transaction(bal)
  }
}

println("initial balance?")
val initial = readInt

transaction(initial)