DISCLAIMER: following the steps below will give you a simple Clojure "installation" with a Repl, and you will be able to run Clojure files. It will be good enough for the first simple steps. After getting first experiences with the simple setup described here you may want to switch to a "real" Clojure setup that includes all Clojure tools and features such as dependency management and most importantly: debugging (which this simple setup does NOT support). Also: some commandline skills are required.

Getting started with Clojure seems to take considerable effort. I knew some Lisp and was mildly interested in Clojure but figuring out what to install to get started was somewhat difficult. And after figuring out what to install I would have to actually install all the stuff as well!

It turned out that just to run a "Hello, World!" program or to type a few Clojure forms into a Repl you don't need all that stuff. A JRE or JDK and three Jar files is enough to get started, no installation required, the simple steps to do this are described below.

This will be good enough to get a first view of Clojure, type some code in the Repl, and run moderately simple Clojure programs (see e.g. hello.clj for the famous "Hello, World!" program or sieve_8_bit.clj for a more sophisticated program). No immediate need to figure out leiningen, tools.deps, deps.edn and all the other tools. (Although at some point you may want to visit https://clojure.org/guides/getting_started for instructions on how to do a full Clojure setup.)

Maybe the simple steps given below are even useful for experienced Clojurians, e.g. to try out a new alpha version without changing their current setup, or to run some Clojure on a computer where they can't or won't install stuff, or to experiment with different Java settings in a "sandbox" without affecting their main Clojure installation.

NOTE: Some commandline skills are required for the steps below, so this will not be for everyone. Also: the steps below are for Windows, but adapting to another OS shouldn't be too hard.

The short version of "from nothing to a working Clojure Repl" is:

• have or download a JRE or JDK
• download three Clojure Jar files
• run java -cp clojure-N.NN.N.jar;spec.alpha-N.NN.N.jar;core.specs.alpha-N.NN.N..jar clojure.main
  or run java -cp clojure-N.NN.N.jar;spec.alpha-N.NN.N.jar;core.specs.alpha-N.NN.N..jar clojure.main hello.clj
• Profit!

The detailed version of the above is:

• clone this repo (or actually: downloading simple-clj.cmd and maybe hello.clj really is all you need to get started)

• download and unzip a JDK e.g. JDK-19 from jdk.java.net (not required if you have a somewhat recent JRE or JDK, I think JRE 8 or better is fine, try java -version to find out if you already have one)

• download three Clojure Jar files, I used

  • https://repo1.maven.org/maven2/org/clojure/clojure/1.11.1/clojure-1.11.1.jar
  • https://repo1.maven.org/maven2/org/clojure/core.specs.alpha/0.2.62/core.specs.alpha-0.2.62.jar
  • https://repo1.maven.org/maven2/org/clojure/spec.alpha/0.3.218/spec.alpha-0.3.218.jar

  which were current a the time of this writing. Newer ones will probably work as well once newer versions are released.

• make some adjustments in simple-clj.cmd (see the comments in the file)

• invoke:

  C:\...\> simple-clj hello.clj
  Hello, World!
  C:\...\>
  

  to run the "Hello, World!" program or type

  C:\...\> simple-clj
  Clojure 1.11.1
  user=> "Hello"
  "Hello"
  user=> ^Z
  
  C:\...\>
  

  to enter the Clojure Repl (Hint: exit the Clojure Repl by pressing CTRL-Z followed by the Enter key)

PrimeClojure.clj and sieve_8_bit.clj were copied from https://github.com/PlummersSoftwareLLC/Primes and are licensed under the BSD-new/BSD-3 license, the remaining files in this repo are licensed under the Unlicense license.

Cheers.