Permutations of a certain length of a list in elixir (v2)

ListPermutations.ex

defmodule ListPermutations do

  def list_permutations(_, 0), do: [[]]
  def list_permutations([], _), do: []
  def list_permutations([h|t], n), do: Enum.map(list_permutations(t, n-1), fn(l) -> [h|l] end) ++ list_permutations(t, n)

end

note: instead of fn(l) -> [h|l] end one could have written &[h|&1] which I don't really like