class Sheet(capacity: Int) {
  val text = new Array[Char](capacity)
  var length = 0
  def appendSymbol(symbol: Char) = {
    this.text(length) = symbol
    length += 1
  }

  def printSheet = {
    text.slice(0, length).foldLeft("")((resultString, char) => resultString + char)
  }
}

object HelloWorld extends App {
  val sheet = new Sheet(100)
  sheet.appendSymbol('d')
  sheet.appendSymbol('e')
  sheet.appendSymbol('a')
  sheet.appendSymbol('f')
  println(sheet.printSheet)
  println(List(1, 2, 3).foldLeft(0)((sum, curr_elem) => sum + curr_elem))
}