derivative in scala

gistfile1.scala

// in scala
// https://twitter.com/my7truth/status/269825587797958656

// 79
def p1(p: Seq[Int]) = p.zipWithIndex.map{case (x,y) => x * (p.size - y - 1)} dropRight 1

// 86
def p2(p: Seq[Int]) = p.zipWithIndex.map(x => x._1 * (p.size - x._2 - 1)) dropRight 1

// 83
def p3(p: Seq[Int]) = p.reverse.zipWithIndex.map(x => x._1 * x._2).drop(1).reverse