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Clojure

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Clojure is a robust, practical, and fast programming language with a set of useful features that together form a simple, coherent, and powerful tool.

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## The Clojure Programming Language

Clojure is a dynamic, general-purpose programming language, combining the approachability and interactive development of a scripting language with an efficient and robust infrastructure for multithreaded programming. Clojure is a compiled language, yet remains completely dynamic – every feature supported by Clojure is supported at runtime. Clojure provides easy access to the Java frameworks, with optional type hints and type inference, to ensure that calls to Java can avoid reflection.

Clojure is a dialect of Lisp, and shares with Lisp the code-as-data philosophy and a powerful macro system. Clojure is predominantly a functional programming language, and features a rich set of immutable, persistent data structures. When mutable state is needed, Clojure offers a software transactional memory system and reactive Agent system that ensure clean, correct, multithreaded designs.

I hope you find Clojure's combination of facilities elegant, powerful, practical and fun to use.

Rich Hickey
author of Clojure

### Learn More
#### Rationale

A brief overview of Clojure and the features it includes

#### Getting Started

Resources for getting Clojure up and running

#### Reference

Grand tour of all that Clojure has to offer

#### Guides

Walkthroughs to help you learn along the way

#### Community

We have a vibrant, flourishing community. Join us!

### Companies Succeeding with Clojure

> “Our Clojure system just handled its first Walmart black Friday and came out without a scratch.”

Anthony Marcar, Senior Architect
Walmart Labs

> “Clojure is a functional programming language from top to bottom. This means that code written in Clojure is very modular, composable, reusable and easy to reason about.”

Chris Price, Software Engineer
Puppet Labs

> “We discussed the existing Clojure community, the maturity of the language itself and the momentum we saw in the industry. Companies are seeing speed to market deliveries ... based on Clojure.”

Dave Elliman, Head of Technology
ThoughtWorks

Read more about Clojure success stories, how the community uses Clojure, and find companies using Clojure.

### Features

Clojure has a set of useful features that together form a simple, coherent, and powerful tool.

#### Dynamic Development

Clojure is a dynamic environment you can interact with. Almost all of the language constructs are reified, and thus can be examined and changed. You can grow your program, with data loaded, adding features, fixing bugs, testing, in an unbroken stream.

#### Functional Programming

Clojure provides the tools to avoid mutable state, provides functions as first-class objects, and emphasizes recursive iteration instead of side-effect based looping. Clojure is impure, yet stands behind the philosophy that programs that are more functional are more robust.

#### LISP

Clojure is a member of the Lisp family of languages. Many of the features of Lisp have made it into other languages, but Lisp's approach to code-as-data and its macro system still set it apart. Additionally, Clojure’s maps, sets, and vectors are as first class in Clojure as lists are in Lisp.

#### Runtime Polymorphism

Systems that utilize runtime polymorphism are easier to change and extend. Clojure offers simple, powerful and flexible mechanisms for runtime polymorphism. Clojure’s protocols and datatypes features add mechanisms for abstraction and data structure definition with no compromises vs the facilities of the host platform.

#### Concurrent Programming

Clojure simplifies multi-threaded programming in several ways. Because the core data structures are immutable, they can be shared readily between threads. Clojure, being a practical language, allows state to change but provides mechanism to ensure that, when it does so, it remains consistent, while alleviating developers from having to avoid conflicts manually using locks etc.

#### Hosted on the JVM

Clojure is designed to be a hosted language, sharing the JVM type system, GC, threads etc. All functions are compiled to JVM bytecode. Clojure is a great Java library consumer, offering the dot-target-member notation for calls to Java. Clojure supports the dynamic implementation of Java interfaces and classes.

### News

- 2025-07-28  Clojure Deref (July 28, 2025)
- 2025-07-20  Clojure Deref (July 20, 2025)
- 2025-07-14  Clojure Deref (July 14, 2025)
- 2025-07-06  Clojure Deref (July 6, 2025)
- 2025-06-27  Clojure Deref (June 27, 2025)

### Upcoming Events

- 2025-11-12  Clojure/Conj 2025

### Nubank

Nubank is one of the world's largest digital banking platforms, serving over 100 million customers across Brazil, Mexico, and Colombia. From its start, Nu has had a spectacular success story with Clojure, running mission-critical software at scale. In 2020, the company acquired Cognitect, the consultancy behind Clojure and the Datomic database.

Through the acquisition, Nubank incorporated a world-class team to assist developers in translating Clojure's ideas into business agility and leverage the company's mission to fight complexity and empower people. Currently, Nu is a key corporate sponsor of Clojure and ClojureScript.

For more information about how Nubank builds products and teams, visit building.nubank.com.br.

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Published 2025-07-29