Getting Started with Clojure
The easiest way to get started with Clojure is through Leiningen.
I'll start creating a new Leiningen project running lein new app clojure-101 in my terminal. It will bootstrap a simple Clojure app.
Now change the directory and enter in the clojure-101 app folder then run lein run. It should display the default message "Hello, World".
I will update the file project.clj and include the Leiningen autorun plugin by including this line :plugins [[lein-auto "0.1.3"]]. The file will become the following:
(defproject clojure-101 "0.1.0-SNAPSHOT"
:description "FIXME: write description"
:url "http://example.com/FIXME"
:license {:name "EPL-2.0 OR GPL-2.0-or-later WITH Classpath-exception-2.0"
:url "https://www.eclipse.org/legal/epl-2.0/"}
:dependencies [[org.clojure/clojure "1.10.1"]]
:main ^:skip-aot clojure-101.core
:target-path "target/%s"
:plugins [[lein-auto "0.1.3"]]
:profiles {:uberjar {:aot :all
:jvm-opts ["-Dclojure.compiler.direct-linking=true"]}})
Look in the line 9.
Now I'll run lein auto run in my terminal and this is the output:
> lein auto run
auto> Files changed: src\clojure_101\core.clj, test\clojure_101\core_test.clj
auto> Running: lein run
Hello, World!
auto> Completed.
Yay! My project is running automatically when I change any file.
This behavior is very useful to learn a new language. I need fast feedback and I don't understand the whole Clojure ecosystem to run REPL and plug that in my editor. I like to follow the easiest path that I already know.
I know how to develop using JavaScript and auto-reload server. I just want the same behavior while getting started with Clojure.
It is so easy that right now I can change the core.clj file and just print another message:
(ns clojure-101.core
(:gen-class))
(defn -main
"I don't do a whole lot ... yet."
[& args]
(println "Hello darkness, my old friend"))
Looking at the terminal, I see the new message "Hello darkness, my old friend".