setup-prompt() {
  local last_res=$? color=$PS1_color_success
  PS1="\w "

  if [[ -d .git ]]; then
    PS1+="$(command git branch --show-current) "
  fi

  if [[ -v SSH_CLIENT ]]; then
    PS1+="$PS1_hostname "
  fi

  if (( last_res )); then
    color=$PS1_color_fail
  fi

  PS1+="\[$color\][$last_res]\[$PS1_color_reset\] $PS1_prompt_sym "
}

PROMPT_COMMAND+=(setup-prompt)

PS1_prompt_sym=λ
PS1_hostname=${HOSTNAME-"$(hostname)"}
PS1_color_fail=$(tput setaf 1)
PS1_color_success=$(tput setaf 2)
PS1_color_reset=$(tput sgr0)