mylc.ex

defmodule MyLc do
  def next({_, :stop}, _), do: []
  
  def next([], _), do: []
  
  def next([current | next], fun) do
    [fun.(current) | next(next, fun)]
  end
  
  def next({iter, {current, next}}, fun) do
    [fun.(current) | next({iter, iter.(next)}, fun)]
  end
  
  defmacro mylc({var, _,[{:inenum, _, [enumerable]}]}, do: block) do
    quote do
      MyLc.next(
        Enum.Iterator.iterator(unquote(enumerable)),
        fn(unquote({var, [], nil})) -> unquote(block) end
      )
    end
  end
end

defmodule Test do
  import MyLc
  
  def test do
    IO.inspect(mylc x inenum 1..5 do
      x + 1
    end)
    
    IO.inspect(mylc x inenum [2,3,4] do
      x * x
    end)
  end
end

Test.test