Fibonacci in Scala

fibonacci.scala

// Test directly from shell using (e.g. input 5):
// scala -i fibonacci.scala -e 'println(fibonacci(5))'
def fibonacci(n: Int) = fibonacci_tail_recursive(n, 1, 0)

def fibonacci_tail_recursive(iter: Int, current: BigInt, last: BigInt): BigInt= {
  if (iter == 0)
    last
  else
    fibonacci_tail_recursive(iter-1, current+last, current)
}