Scala filter on a list by index

Question

I wanted to write it functionally, and the best I could do was:

list.zipWithIndex.filter((tt:Tuple2[Thing,Int])=>(tt._2%3==0)).unzip._1

to g

Answer 1

A nice, functional solution, without creating temporary vectors, lists, and so on:

def everyNth[T](xs: List[T], n:Int): List[T] = xs match {
  case hd::tl => hd::everyNth(tl.drop(n-1), n)
  case Nil => Nil
}