{:check ["true"]}

Index

Getting Started

Prerequisite: JVM

Clojure compiles its programs natively to Java bytecode, so you will need a Java Runtime Environment (JRE) installed.

Clojure recommends JRE 1.8 (Java 8 runtime environment).

$ java -version
openjdk version "1.8.0_152-release"
OpenJDK Runtime Environment (build 1.8.0_152-release-1056-b12)
OpenJDK 64-Bit Server VM (build 25.152-b12, mixed mode)

However, we have confirmed that everything works fine with the latest JRE.

$ java -version
openjdk version "14.0.1" 2020-04-14
OpenJDK Runtime Environment (build 14.0.1+7)
OpenJDK 64-Bit Server VM (build 14.0.1+7, mixed mode, sharing)

Cli

Clojure Installer

Supported platforms: https://clojure.org/guides/getting_started#_clojure_installer_and_cli_tools
1. Linux
2. macos
3. Windows
A successful installation will provide you the clj command.
- It is a Read-Eval-Print-Loop (REPL) environment for Clojure.
- It is a runtime of Clojure programs.

As REPL

Using clj as REPL: we can interactively evaluate code snippets.

$ clj
Clojure 1.10.1
user=> (println "Hello")
Hello
nil
user=>

As scripting language

Using clj as runtime environment: we can write small single-file Clojure programs and run them with clj.

learn.clj

(defn christmas-tree [n]
  (dotimes [i n]
    (let [spaces (apply str (repeat (- 3 i) " "))
          stars (apply str (repeat (inc (* 2 i)) "*"))]
      (println (str spaces stars))))
  (println (str (apply str (repeat (dec n) " ")) "|")))

(christmas-tree 4)

We can run it:

$ clj learn.clj
   *
  ***
 *****
*******
   |

As build tool for larger projects

The command clj can also be used to build larger projects. More details can be found:

https://clojure.org/guides/deps_and_cli