Author John M. Chambers was one of the principle designers of the S Language upon which R is based.  Don't make the mistake I did, though, you don't want to read this book first if you are new to R!  This book is for intermediate to advanced R programmers who want to take their R skills to the next level such as creating packages, classes and external interfaces.  But, eventually, you will buy this book and you'll be happy you did.  To order this book from Amazon, click the link: Software for Data Analysis: Programming with R (Statistics and Computing).