with.ex

defmodule Foo do

  def bar do
    with {:ok, width} <- Map.fetch(opts, :width),
      {:ok, height} <- Map.fetch(opts, :height) do
      {:ok, width * height}
    else
      :error ->
	{:error, :wrong_data}
    end
  end

end

defmodule Foo do

  def bar do
    with {:ok, width} <- Map.fetch(opts, :width),
      {:ok, height} <- Map.fetch(opts, :height),
      do: {:ok, width * height},
      else: {:error, :wrong_data}
  end

end