Xtend

Xtend is a statically-typed programming language for the Java Virtual Machine (JVM) designed to be a more productive and readable alternative to Java. It integrates with the Java ecosystem, and Xtend programs compile to Java bytecode and run on the JVM. The language is part of the Eclipse project ecosystem and is built on the Xtext framework, providing strong IDE support and DSL capabilities.

Xtend aims to reduce boilerplate and improve readability through features such as type inference, concise function declarations, and immutable by default variables. It uses val for immutable and var for mutable local variables, and def to declare methods with optional explicit return types. The language also supports extension methods, allowing developers to add new behavior to existing Java types without modifying their source. Other core capabilities include lambda expressions and closures, rich collection literals, range-based for loops, and fluent-style APIs. Xtend supports Java interoperability—Xtend code can instantiate and interact with Java classes, and Java code can be used from Xtend without special wrappers. The generated code is standard Java bytecode, ensuring compatibility with existing Java tooling and runtimes.

Historically, Xtend was developed within the Eclipse/Xtext project to provide a cleaner Java-like language and to facilitate DSL development. It remains available as an option within the JVM language landscape, favored by teams seeking a productive syntax and strong Java integration while preserving Java interoperability.