Builder 1.0.0 has been released. Builder is a simple library that makes generating XML and HTML markup rather simple. Version 1.0.0 has changed the interface in several ways to make Builder more reliable and easy to use, but has broken backwards compatibility with versions prior to 1.0.0. If you are using the builder gem, use one of the following:

require 'builder', '~> 0.1' # to use the old interface

require 'builder', '~> 1.0' # to use the new interface.

Although a given application must use either one or the other, both versions may be installed on a system without conflict.