How to generate the power set of a set in Scala

Question

I have a Set of items of some type and want to generate its power set.

I searched the web and couldn\'t find any Scala code that adresses this specific task.

Answer 1

Can be as simple as:

def powerSet[A](xs: Seq[A]): Seq[Seq[A]] = 
  xs.foldLeft(Seq(Seq[A]())) {(sets, set) => sets ++ sets.map(_ :+ set)}

Recursive implementation:

def powerSet[A](xs: Seq[A]): Seq[Seq[A]] = {
  def go(xsRemaining: Seq[A], sets: Seq[Seq[A]]): Seq[Seq[A]] = xsRemaining match {
    case Nil => sets
    case y :: ys => go(ys, sets ++ sets.map(_ :+ y))
  }

  go(xs, Seq[Seq[A]](Seq[A]()))
}