Introduction to Clojure & JVM
Understand what Clojure is, its place in the JVM ecosystem, and set up your development environment.
Introduction to Clojure & JVM is a free Clojure Functional Programming & JVM Backend Development lesson on CoddyKit — lesson 1 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Clojure Functional Programming & JVM Backend Development learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.
Discover Clojure
Clojure is a modern, dynamic, functional Lisp built for concurrency. It runs on the JVM, so you inherit a huge ecosystem.
Clojure's Core Ideas
Clojure stands on four ideas: functional style, immutable data, built-in concurrency, and a consistent Lisp syntax of parentheses.
Clojure on the JVM
Clojure compiles to JVM bytecode, which hands you the Java ecosystem, mature runtime performance, and write-once cross-platform reach.
Understanding the JVM
The JVM executes Java bytecode and handles memory and garbage collection, running your code consistently across operating systems.
Installing Clojure Tools
You work with Clojure through the official CLI tools, which run programs, manage dependencies, and launch the REPL.
Your First Clojure Code
Here is Hello World. Note the parentheses — that is Lisp. You define a -main function and call println.
(ns coddykit.core
(:gen-class))
(defn -main
"The entry point for our program."
[& args]
(println "Hello, CoddyKit!"))Decoding Your First Code
Decoding it: ns sets a namespace, defn defines a function, and a call is just (function args) wrapped in parens.
Executing Your Code
Save the file and run it with clj -M hello.clj; the Clojure runtime executes your main and prints the result.
Discover the REPL
The REPL (Read-Eval-Print Loop) is an interactive console — type code, see results instantly. It is the heart of Clojure development.
Clojure Fundamentals
Based on what we've learned, choose the best description of Clojure's relationship with the JVM.
What We've Learned
Recap: Clojure is a functional Lisp on the JVM built on immutability and concurrency, and you ran Hello World and met the REPL.
Frequently asked questions
Is the “Introduction to Clojure & JVM” lesson free?
Yes — the full text of “Introduction to Clojure & JVM” is free to read here on the web, and the Clojure Functional Programming & JVM Backend Development course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Clojure Functional Programming & JVM Backend Development course, upgrade to CoddyKit PRO.
What will I learn in “Introduction to Clojure & JVM”?
Understand what Clojure is, its place in the JVM ecosystem, and set up your development environment. You practise Clojure Functional Programming & JVM Backend Development with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start Clojure Functional Programming & JVM Backend Development?
No prior experience is required. Clojure Functional Programming & JVM Backend Development on CoddyKit is structured for beginners through advanced learners; this is — lesson 1 of 4, so you can start here or from the beginning and move at your own pace.
How long does the “Introduction to Clojure & JVM” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this Clojure Functional Programming & JVM Backend Development lesson?
Yes. Every Clojure Functional Programming & JVM Backend Development lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.
All lessons in this course
- Introduction to Clojure & JVM
- Core Data Structures & Syntax
- REPL-Driven Development Workflow
- Destructuring and Working with Keywords