destruct.ex

defmodule Struct do
  defp filter_nil({_,nil}), do: false
  defp filter_nil(_),       do: true

  def destruct(%{:__struct__ => _} = v), do: Map.from_struct(v) |> destruct
  def destruct(v) when is_list(v),       do: Enum.map(v, &destruct/1)
  def destruct(v) when is_map(v),        do: Enum.filter_map(v, &filter_nil/1, &destruct/1) |> Enum.into %{}
  def destruct({k,v}),                   do: {k,destruct(v)}
  def destruct(v),                       do: v
end