To get a prompt which indicates Git-branch in Zsh

Question

I run the following codes separately as my prompt unsuccessfully in .zshrc. This suggests me that apparently I do not have a program called __git_ps1. It is not in MacPorts.

Answer 1

Thank you for the links!

I made the following prompt based on them

     # get the name of the branch we are on
     git_prompt_info() { 
         git branch | awk '/^\*/ { print $2 }'
     }
     get_git_dirty() { 
       git diff --quiet || echo '*'
     }

     autoload -U colors
     colors     
     setopt prompt_subst

     PROMPT='%{$fg[blue]%}%c %{$fg_bold[red]%}$(git_prompt_info)$(get_git_dirty)%{$fg[blue]%} $ %{$reset_color%}'                                           

     RPROMPT='%{$fg[green]%}%1(j.%j.)'        

Please, suggest any improvements.