Listing 2.1: A Gemfile for the demo app.

Note that Listing 2.1 is identical to Listing 1.9.

As in Section 1.4.1, we’ll install the local gems while suppressing the
installation of production gems using the --without production option:

$ bundle install --without production
$ bundle update
$ bundle install

Recall that if Bundler complains about a readline error, try adding gem
’rb-readline’ to your Gemfile