Snow is a GUI description language for Swing, in the vein of XUL and SwiXml but based on Lisp rather than XML.

It is a declarative language: the code is tree-structured, like XML and any Lisp-based language, and its structure mirrors the hierarchy of the GUI components. Furthermore, layout is specified using a CSS-like embedded language, and the connection with application code is demanded to data binding and event listeners (which can be coded in Lisp or in Java).

Like most languages built on Lisp, it fully retains the underlying language features, including functional and imperative programming, OO support, garbage collection, dynamic typing, runtime incremental compilation, a powerful macro system, advanced error handling, and so on...