What is jruby?

JRuby is a tool that lets you run code written in the Ruby programming language on the Java platform. Normally, Ruby and Java are separate worlds with their own setups, but this project bridges them. The main benefit is that it lets developers write Ruby code that can directly interact with existing Java code, and it also lets Java applications run Ruby scripts inside them. At a high level, it works by rebuilding the Ruby interpreter, the engine that reads and executes Ruby code, using Java. Once you have it set up, you can run a Ruby file by passing it to the tool, much like you would with standard Ruby. The project is built to compile with common Java tools, and it essentially packages the Ruby language into a format that the Java ecosystem can understand and work with directly. This would be useful for teams that already have a lot of Java infrastructure but want to take advantage of Ruby, often used for scripting or rapid development. For example, a company with a large Java application could use this to let team members write automation scripts or plugins in Ruby, and those scripts could call directly into the Java code already running in the application. Conversely, a Ruby developer could tap into Java libraries that don't normally exist in the Ruby world. The project has a long history, with a large list of contributors and community involvement. Beyond that, the README doesn't go into much detail on specific architectural decisions or tradeoffs, but the core idea is straightforward: it brings two major programming ecosystems together in a way that lets each one use the other's strengths.