Writing Web3 Apps with Clojurescript

ophy@newsletter.paragraph.com (ophy.eth) — Fri, 10 Dec 2021 22:36:10 GMT

Clojure has been my favorite language for a long time. It is not without its faults, but it is the language in which I can express my ideas in the most efficient way. It has a powerful macro system that lets you mold the language to your needs. Most Clojure code can run on the JVM as well as in a Javascript runtime (as Clojurescript). This lets us leverage two rich package ecosystems with a convenient lisp syntax.

While much of the code will be self-explanatory, a familiarity with Clojure (or other lisps) will be helpful.

Getting Started

Writing Clojure code is pretty simple and doesn’t require much boilerplate. We will need a few dependencies though.

Installing Dependencies

Install Clojure by following this guide:

https://clojure.org/guides/getting_started

Then install shadow-cljs:

https://github.com/thheller/shadow-cljs

Initialize Project

I like to keep all my projects under ~/Developer, so I run this from there, but from whichever directory you want to create your project in, run the following code in your terminal:

npx create-cljs-project hello-web3

This will create a new directory called hello-web3 and within it create some of the files we need to get started.

One of the quirks Clojurescript inherited from Java is namespacing and directory structure.

Create the following file: src/main/helloweb3/frontend/app.js and put this in it:

(ns helloweb3.frontend.app)

(defn init []
  (println "Hello Web3"))

In shadow-cljs.edn, replace the empty :builds map with the following:

{
...
  :builds
  {:frontend
   {:target :browser
    :modules {:main {:init-fn helloweb3.frontend.app/init}}
    }}}

Create the file public/index.html

    hello web3
  
  
    
    
  

"><!doctype html>
<html>
  <head>
    <meta charset="utf-8" />
    <title>hello web3</title>
  </head>
  <body>
    <div id="root"></div>
    <script src="/js/main.js"></script>
  </body>
</html>