while2.exs

defmodule WhileLoop do
  defmacro while(condition_expression, do: do_block) do
    quote do
      try do
        for _ <- Stream.cycle([:fine]) do
          if unquote(condition_expression) do
            unquote(do_block)
          else
            throw :break
          end
        end
      catch
        :break -> :ok
      end
    end
  end
end