Pulled straight from the source code using RDoc, this reference work documents all of the core classes and modules (like String, Array, Symbol, etc). These are the API documents for the base classes and modules in the current stable release.
Book Description
Ruby is a dynamic, reflective, general-purpose object-oriented programming language that combines syntax inspired by Perl with Smalltalk-like features. Ruby originated in Japan during the mid-1990s and was first developed and designed by Yukihiro “Matz” Matsumoto. It was influenced primarily by Perl, Smalltalk, Eiffel, and Lisp.
Ruby supports multiple programming paradigms, including functional, object oriented, imperative and reflective. It also has a dynamic type system and automatic memory management; it is therefore similar in varying respects to Smalltalk, Python, Perl, Lisp, Dylan, Pike, and CLU.