Prompt Mix env on IEX (with colors)

.iex.exs

env = case System.get_env("MIX_ENV") || "dev" do
  "prod" -> IO.ANSI.red() <> "prod" <> IO.ANSI.reset()
  "dev" -> IO.ANSI.green() <> "dev" <> IO.ANSI.reset()
  "test" -> IO.ANSI.green() <> "test" <> IO.ANSI.reset()
  mix_env -> IO.ANSI.yellow() <> mix_env <> IO.ANSI.reset()
end

IEx.configure(
  default_prompt: "%prefix(#{env},%counter)>",
  alive_prompt: "%prefix(#{env},%node,%counter)>"
)