Big Fat Rails
by Mitch Guthrie
Publisher: bigfatrails.com 2012
Number of pages: 53
Big Fat Rails is a book designed around teaching Ruby on Rails in a precept upon precept fashion. Learning a little at a time and building in complexity as the book moves forward. Both theory and practice driving your knowledge. If you are a beginner and looking to learn Ruby on Rails, the purpose of this book is to simply get you there in small, manageable steps.
Download or read it online for free here:
by Bruno R. Preiss
The primary goal of this book is to promote object-oriented design using Ruby and to illustrate the use of the emerging object-oriented design patterns. The book shows how these patterns are used to create good software designs.
by Minero Aoki
The RHG is a book that explains how the ruby interpreter (the official C implementation of the Ruby language) works internally. To fully understand it, you need a good knowledge of C and Ruby. This book is going to investigate ruby as a whole.
by Huw Collingbourne - No Starch Press
A comprehensive tutorial to the Ruby language. Each chapter is accompanied by ready-to-run source code for all the examples. There is also an Introduction which explains how to use the source code in Ruby In Steel or any other IDE of your choice.
by why the lucky stiff
This is just a small illustrated online-only Ruby book. It won't crush you. It's light as a feather (because I haven't finished it yet--hehe). And there's a reason this book will stay light: because Ruby is simple to learn.