Scala tail recursion example. Returns the "nth" position in the fibonacci sequence. Tail recursive because evaluation is completed and passed to next call, nothing else needs to be evaluated after return. This lets scala compiler optimize this.

tail-recursion

def fibNum(pos: Int) = {
  def go(n: Int, curr: Int, next: Int): Int = {
    if (n == 0) curr
    else go(n-1, next, curr+next)
  }

  go(pos, 0, 1)
  
}