Tests to the left of me, types to the right: how not to get stuck in the middle of a ruby execution

Ruby is a popular dynamic scripting language that permits terse, expressive code, but provides no static checks to detect errors before running the program. To address this, we have developed Diamond-back Ruby (DRuby), a tool that blends the benefits of static and dynamic typing. This paper briefly describes the main features of DRuby, which we will present in a tool demonstration. The presentation will concentrate on the development of a small, statically typed Ruby program, illustrating how DRuby might be used in practice. The audience will learn about some of the practical design decisions that went into DRuby, and how to use it to develop a type-safe Ruby program.