Installing Memcache for use with Ruby/Rails and Postgres

There’s an article in the community section https://www.digitalocean.com/community/articles/how-to-install-and-use-memcache-on-ubuntu-12-04 that has instructions about installing memcache.

The article says that PHP and mysql should be installed on the server: “Additionally, you should have MySQL and PHP installed on the virtual server. sudo apt-get install mysql-server php5-mysql php5 php5-memcache”

However, I’m not using PhP or mysql in my app. Do PHP and mysql need to be installed for the purpose of installing memcache, or did the article just assume that memcache would be used in an application with Php and mysql. I think the article suggests that PHP is needed to actually set up memcache because it talks about PEAr (a php package) being needed to store the repository

“The next step is to install php-pear, the repository that stores memcache. sudo apt-get install php-pear”

In my case, since I’m using Ruby/rails (and postgres), what should I do to install memcache?