average.hs

avg xs = sm/lng
    where (sm,lng) = foldl avgr (0,0) xs
          avgr (s,l) x = (x+s,1+l)     

Average.scala

def avg(xs:List[Int]):Float={
  val (sum,length)=xs.foldLeft((0,0))( { case ((s,l),x)=> (x+s,1+l) })
  sum/length
}

Average of a list in one pass using tupling (banana split?)