cli tool in Haskell

cli.hs

#!/usr/bin/env stack --silent runhaskell
{-# LANGUAGE OverloadedStrings #-}
import Console.Options
import Turtle
import Data.Text hiding (empty)

main = defaultMain $ do
  programName "cli"
  programDescription "personal CLI utilities"

  command "help" $ do
    action $ \_ -> do
      echo "Usage: cli [command] [arguments]"
      echo ""
      echo "Available commands:"
      echo "  posgres     start/stop posgresql server"
      echo "  version     prints version"
      echo ""

  command "version" $ do
    action $ \_ -> do
      echo "cli version 0.0.1"

  command "postgres" $ do
    command "start" $
      action $ \toParam -> do
        code <- shell "tmux new-session -d -s \"postgresql\" -n posgres-server postgres -D /usr/local/var/postgres" empty
        guard (code == ExitSuccess)
        echo "started"

    command "stop" $
      action $ \toParam -> do
        shell "tmux send-keys -t \"postgresql\" C-c C-d" empty
        echo "stopped"