Gemfile

# This file contains information about which libraries
# our application needs in order to run.  In Ruby,
# these libraries are called "gems."
#
# Get it?  Ruby?  Gems?  Ha. ha. ha.

source "https://rubygems.org"  # Download our libraries from rubygems.org

gem "sinatra",    "~> 1.4.5"   # Sinatra is the web framework we're using
gem "datamapper", "~> 1.2.0"   # DataMapper is the database library we're using

# "development" refers to our local copy, running on our own computer
group :development do
  gem "sqlite3"                # Use the SQLite3 database locally
  gem "dm-sqlite-adapter"      # Allow DataMapper to use SQLite3
  gem "rerun"
end

# "production" refers to a copy running on a remote server
# (Heroku in our case.)
group :production do
  gem "dm-postgres-adapter"    # Heroku uses the PostgreSQL database
end