title: Configure nix-shell to use a shell other than Bash?
body: <p>I'm on NixOS 15 and nix-shell v1.10.  I use Zsh as my main shell now, and would like to use it in conjuction with Oh-My-Zsh within the nix-shell as well when I'm working in development environments built by a Nix expression.</p>
  
  <p>If it helps, here is one of the Nix environments I have set up for a Rails project:</p>
  
  <pre><code>with import &lt;nixpkgs&gt; {}; {
    cannyFreeRadicalEnv = stdenv.mkDerivation rec {
      name = "canny-free-radical-env";
      version = "0.1";
      src = ./.;
      buildInputs = [
          stdenv
          ruby_2_2_2
          bundler_HEAD
          zlib
          postgresql94
          sqlite
      ];
    };
  }
  </code></pre>
  
  <p><strong>** Edit **</strong></p>
  
  <p>Running the command this way does not indicate in the CLI prompt that I'm in the nix-shell.  Is there an easy way to detect this so that I can script it up quickly in my <code>zshrc</code>?</p>