Gosu is a statically-typed programming language that runs on the Java Virtual Machine released under the Apache 2. This general-purpose programming language is used in several open-source software projects including SparkGS and Ragnar DB among several others, and is widely used in the insurance industry via Guidewire Software's commercial products. The language borrows from several existing languages including Java, C#, and ECMAScript. A notable and unique feature is its Open Type System, which allows the language to be easily extended to provide compile-time checking and IDE awareness of information that is typically checked only at runtime in most other languages. Also of note is the language's ability to serve as both a full-featured general purpose language and as a concise scripting l