kacat

# for future reference to obfuscation best practices
  i |> (&-/2).(offset) # =:= i-offset (...)
  |> calculate_2017_date()
  |> map_to_mdy

# Keeping this for the list-cycling line only
        defp calculate_date(d, months \\ Enum.to_list(1..12), year \\ 1900, month \\ 1) do
        [current_month|rest] = months
        new_months = Enum.reverse([current_month|Enum.reverse(rest)])

# create functions dynamically with a macro that uses
# a recursive helper module
defmodule A do
  defmodule B do
    def lofa(5, acc) do
      q =
        quote do
          def vmi(unquote(5)), do: unquote(5)*unquote(5)
        end
      unwrapper([q|acc])
    end
    def lofa(i, acc) do
      q =
        quote do
          def vmi(unquote(i)), do: unquote(i)*unquote(i)
        end
      lofa(i+1, [q|acc])
    end

    def unwrapper(list) do
      for l <- list, do: l
    end
  end
  defmacro make_vmi(i) do
    B.lofa(i, [])
  end
end

# from payroll_date.ex where map_date = %{year: y, month: m, day: d}
day_of_week =
  map_date
  |> Map.values
  |> (fn [d,m,y] -> [y,m,d] end).()
  |> (&Kernel.apply(Calendar.ISO, :day_of_week, &1)).()