.clj File — Clojure Source Code

Clojure is a dynamic, functional programming language created by Rich Hickey in 2007 that runs on the Java Virtual Machine. CLJ files contain source code in a modern Lisp dialect designed for practical concurrent programming. Clojure emphasizes immutable data structures (persistent vectors, maps, and sets implemented with structural sharing for efficiency), first-class functions, lazy sequences, and a sophisticated state management model with atoms, refs, and agents for different concurrency patterns. The language's homoiconic syntax (code is data, data is code) enables powerful metaprogramming through macros. Clojure interoperates seamlessly with Java, providing access to the entire Java ecosystem. ClojureScript compiles Clojure to JavaScript for frontend development, often paired with React through the Reagent or Re-frame libraries. The language is used in financial services (Nubank, the world's largest digital bank), data processing, and full-stack web development. Core.async provides CSP-style concurrency (Go channels), and the spec library enables runtime data validation and generative testing. Clojure's philosophy prioritizes simplicity and data-oriented programming.