LeftPad in Scala

object Main {
  def main(args: Array[String]) {
    println(leftPad("1", 1));
    println(leftPad("2", 2));
    println(leftPad("3", 3));
    println(leftPad("4", 4));
    println(leftPad("5", 5));
    println(leftPad("hello", 7));
    println(leftPad("foo",  6));
    println(leftPad("foo", 3));
    println(leftPad("foobar", 3));
    println(leftPad("foo", 6, '?'));
  }
  
  def leftPad(str:String, 
              paddedLength:Int, 
              ch:Char ='.' ) : String = {
    var remLength = paddedLength - str.length;
    if (remLength <= 0) {
      return str;
    }
    val builder = StringBuilder.newBuilder
    for( a <- 0 until remLength){
      builder.append(ch);
    }
    builder.append(str);
    return builder.toString();
  }
}