Okay... so it's kinda tough to start a web project in Clojure. Sure, there's Pedestal, but that's pretty much Clojure wrapped around a 15 year old architecture. Yuck.
So, what's this year's architecture? I think it's
single page apps talking via web sockets to the server... but
the communications is abstracted as core.async messages.
That means the app is as responsive as 90s style client/server apps rather than being 70s style green screen apps (yeah, I'm opinionated but in general, I do things about it).
What do I think the best stack for doing web development looks like?
- Om for the UI
- core.async for messaging (including across web sockets)
Not much else. Basically, all messaging between all components goes through
core.async and that way, all the stuff about where the message is going, etc.
is abstracted away. Boom, your app is just about message passing, not about
client/server, HTTP/REST, etc. It's just about messages.
And there you have it.
A big part of using Clojure is a simple, fast workflow where you can make a change and see the change in real time. This workflow is part of Spiffy.
You need to start 2 REPL sessions... one for the server part of your code and the other for the client part of your code. I do this via emacs and Cider.
I start two emacs sessions:
emacs src/cljs/spiffy/main.cljs &
emacs src/clj/spiffy/server.clj &
And then I start a compilation session for the CLJX and ClojureScript code:
lein pdo cljx auto, cljsbuild auto dev
That kicks off parallel cljx and cljs compilers... so any
change to the Cljx files will trigger a ClojureScript compilation
and that means each time we reload the web page, we'll have the
most recent version of the code.
In one of the emacs sessions, I change the theme with M-x load-theme.
In the case of the ClojureScript emacs session, the theme is light and
in the Clojure session, the theme is dark.
In each of the emacs sessions, I start a REPL via C-c M-j or M-x cider-jack-in.
Once the REPLs are started, in the ClojureScript session, I start the ClojureScript REPL:
user> (require 'spiffy.server)
nil
user> (spiffy.server/run-cljs-repl)
Type `:cljs/quit` to stop the ClojureScript REPL
nil
cljs.user>
And in the Clojure session, I start the web server:
user> (require 'spiffy.server)
nil
user> (ns spiffy.server)
nil
spiffy.server> (start-server)
Running
#<server$run_server$stop_server__8801 org.httpkit.server$run_server$stop_server__8801@f9008b0>
spiffy.server>
Then I load the page at http://localhost:8080 and boom... I have a web page hooked into both REPLs.
We can test the ClojureScript REPL:
cljs.user> (ns spiffy.main)
nil
spiffy.main> (swap! app-state assoc :text "Wombat")
And boom, in the browser, we see the text in the main component change.
Spiffy is dual licensed under the Eclipse Public License, just like Clojure, and the LGPL 2, your choice.
A side note about licenses... my goal with the license is to make sure the code is usable in a very wide variety of projects. Both the EPL and the LGPL have contribute-back clauses. This means if you make a change to Spiffy, you have to make your changes public. But you can use Spiffy in any project, open or closed. Also, the dual license is meant to allow Spiffy to be used in GPL/AGPL projects... and there are some "issues" between the FSF and the rest of the world about how open the EPL, the Apache 2, etc. licenses are. I'm not getting caught in that deal.
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