Code to enumerate permutations in Scala

Question

I coded a function to enumerate all permutations of a given list. What do you think of the code below?

def interleave(x:Int, l:List[Int]):List[List[Int]] = {         


        

Answer 1

def permutator[T](list: List[T]): List[List[T]] = {

  def _p(total: Int, list: List[T]): List[List[T]] = {
    if (total == 0) {
      // End of the recursion tree
      list.map(List(_))
    } else {
      // Controlled combinatorial 
      // explosion while total > 0          
      for (i <- list;
           j <- _p(total - 1, list)) 
        yield { i :: j }

      // It is a recursion tree to generate the 
      // permutations of the elements
      // --------------------------------------
      // total = 0 => _p returns 3 elements (A, B, C) 
      // total = 1 => _p returns 3 * 3 List(List(A, A)...
      // total = 2 => _p returns 3 * 3 * 3 elements List(List(A, A, A)...

    }
  }

  _p(list.length - 1, list)
}

permutator(List("A", "B", "C"))

// output:
List(A, A, A),List(A, A, B),List(A, A, C),List(A, B, A),List(A, B, B),
List(A, B, C),List(A, C, A),List(A, C, B),List(A, C, C),List(B, A, A),
List(B, A, B),List(B, A, C),List(B, B, A),List(B, B, B),List(B, B, C),
List(B, C, A),List(B, C, B),List(B, C, C),List(C, A, A),List(C, A, B),
List(C, A, C),List(C, B, A),List(C, B, B),List(C, B, C),List(C, C, A),
List(C, C, B),List(C, C, C)