A demonstration of writing a Node.js Express app using ClojureScript.

This repo contains the same tiny hello world app, set up with each of the major ClojureScript compilation tools.

Standalone

This uses cljs.jar and a custom build script as described in the ClojureScript Quick-Start.

It also includes a small wrapper shell script to download ClojureScript if it's not there already, and run the build.

cd standalone
./build.sh
node npmdemo.js

Figwheel

Using lein-figwheel. This is the most mature and complete tool out there, and is generally what I recommend using. The code looks slightly different here because it needs to be reloadable.

This version gives you hot code reloading, a ClojureScript REPL, and the possibility to connect with nREPL (e.g. with Emacs/CIDER).

Dev mode:

cd figwheel
lein figwheel

In a separate terminal

node npmdemo-dev.js

Production build:

lein cljsbuild once prod
node npmdemo.js

Shadow-cljs

The new kid on the block. Meant to make configuration easier. Should feel more familiar when coming from Node.

cd shadow-cljs
npm install

Dev mode:

# compile once
npx shadow-cljs compile app
# watch + reload + REPL
npx shadow-cljs watch app
node npmdemo.js

# to actually connect to the REPL (while node process is running)
npx shadow-cljs cljs-repl app

Production build:

npx shadow-cljs release app
node npmdemo.js

Boot

Advanced build tool. Can also offer live-reloading, a ClojureScript repl and an nREPL server. Unfortunately live-reloading is not yet implemented for Node. (see adzerk-oss/boot-reload #68)

Start the dev compilation and watcher

cd boot
boot dev

In another terminal

cd target
node npmdemo.js

For a production build

boot build

Lumo

Lumo is not a compilation tool (although it has experimental support for use as a compiler), instead it's a ClojureScript runtime based on Node.js. You can think of it as Node+ClojureScript bundled into a single executable. This makes it behave more like other interpreted languages, i.e. you can just launch it with a script without having to do a separate compilation step.

It will find dependencies in node_modules, so you can use it with npm/yarn.

cd lumo
npx lumo-cljs src/npmdemo/core.cljs