Tenzing, the awesome Clojurescript application template
Tenzing is a Clojurescript template offering the following features:
- Incremental Clojurescript compilation
In contrast to some of the options out there it is opinionated in the following ways:
- Tenzing uses Boot instead of Leiningen (see below)
- Tenzing does not provide a backend layer (see below)
- Tenzing allows you to choose between Om, Reagent and others
Many Leinigen plugins come with an `auto` task that allows similar behavior. If you want to run multiple of those tasks it's usually done by starting multiple JVM instances which can lead to high memory usage. Boot allows this sort of behaviour to reside in one JVM process while making sure that build steps don't interfere with each other.
You can learn more about Boot in a blog post by one of the authors, its github project or a blog post I wrote about it. Mimmo Costanza's modern-cljs tutorial also uses Boot throughout - Tutorial 2 walks through the setup of a typical Boot-based development environment.
If you figure out that you need a Clojure based backend down the road it's simple to either add it yourself or create it as a standalone service that's being used by your clients.
Please, also consider offline first as an approach for building early iterations of your application.
If you're wondering how files are served during development: there is a boot task `serve` that allows you to serve static files.
Create a Project
To create a new project, install boot and run:
$ boot -d boot/new new -t tenzing -n your-app
Template options are specified using the
-a switch. For example:
$ boot -d boot/new new -t tenzing -n your-app -a +reagent -a +test
Alternatively, if you have leiningen installed, you can run
$ lein new tenzing your-app
or to specify options:
$ lein new tenzing your-app +reagent +test
There are a bunch of options that determine what your newly created project will contain:
+omprovides a basic Om application and adds relevant dependencies
+reagentprovides a basic Reagent application and adds relevant dependencies
+rumprovides a basic Rum application and adds relevant dependencies
+gardensets up Garden and integrates into the build process
+sasssets up Sass and integrates into the build process (requires libsass)
+lesssets up Less and integrates into the build process.
+testadds a cljs test-runner and adds a
+devtoolsadds a cljs-devtools through boot-cljs-devtools
+diracadds a dirac through boot-cljs-devtools.
If you want to add an option, pull-requests are welcome.
After you installed Boot you can run your Clojurescript application in "development mode" by executing the following:
$ boot dev
After a moment of waiting you can head to
localhost:3000 to see a small sample app. If
you now go and edit one of the Clojurescript source files or a SASS
file (if you've used the
+sass option) this change will be picked up
by Boot and the respective source file will get compiled. When a
compiled file changes through that mechanism it will get pushed to the
If you used the
+test option, then you'll be able to run unit
boot test. Use
boot auto-test to have tests
automatically rerun on file changes.
Connecting to the browser REPL
After you started your application with
boot dev there will be a
line printed like the following:
nREPL server started on port 63518 on host 0.0.0.0
This means there now is an nREPL server that you can connect to. You
can do this with your favorite editor or just by running
boot repl --client in the same directory.
Once you are connected you can get into a Clojurescript REPL by
(start-repl). At this point I usually reload my browser one
last time to make sure the REPL connection is properly setup.
Now you can run things like
(.log js/console "test"), which should
print "test" in the console of your browser.
How it works
If you look at the
run tasks in the
build.boot file of
your newly created project you will see something like the following:
(deftask build  (comp (speak) (cljs) (sass :output-dir "css"))) (deftask run  (comp (serve) (watch) (cljs-repl) (reload) (build)))
Basically this composes all kinds of build steps into a unified
task that will start our application. From top to bottom:
build task consists of three other tasks:
speakgives us audible notifications about our build process
sasswill compile Sass source files to CSS
Now if we just run
boot build instead of the aforementioned
boot dev we will compile our Clojurescript and Sass exactly once and then
the program will terminate.
This is where the
run task comes in:
servestarts a webserver that will serve our compiled JS, CSS and anything else that is in
watchwill watch our filesystem for changes and trigger new builds when they occur
cljs-replsets up various things so we can connect to our application through a browser REPL
reloadwill watch the compiled files for changes and push them to the browser
builddoes the things already described above
Please note that all tasks, except the one we defined ourselves have
extensive documentation that you can view by running
boot <taskname> -h (e.g.
boot cljs-repl -h).
Writing build artifacts to disk
By default, none of the tasks in projects generated by tenzing output any files.
For example, when running the
dev task, your project's source and resources are
compiled to a temporary boot fileset and served from there. When boot quits, the
fileset is no longer available.
This is actually boot's default and, at first, might sound like a strange choice for a build tool!
However, these managed filesets are at the core of boot's philosophy and provide it with
many advantages over declarative, stateful build tools. See the boot homepage or the
filesets wiki entry] (https://github.com/boot-clj/boot/wiki/Filesets) for more info on these concepts.
So how do you output your built project to disk so that you can deploy it for example?
Simple! Boot has a [built-in
(https://github.com/boot-clj/boot/blob/master/doc/boot.task.built-in.md#target) that you can can compose with other tasks to
output their results to a given directory (by convention the directory is named
To build a tenzing project with the production settings and output the results to disk you would run the following:
$ boot production build target
If you look in your project directory now, you will see a
target directory containing the
output of all of the tasks in this chain. By default, this directory is cleaned every time
boot, unless you pass the
no-clean option to the
Should you need to filter, copy, move or rename the output files, or change the directory
sift task will help you do this. If you have complex post-processing needs
or want to save typing at the command line, it's a simple matter to define your own tasks.
Since Tenzing comes without a backend you can easily deploy your app
to Amazon S3 or even host it in your Dropbox. To do that just copy the
target/ to your desired location.
PS. I'm also working on a tool called Confetti
🎉that helps you setting up static sites on AWS infrastructure. It's a bit more aimed at people that deploy and manage many static sites but you should probably check it out either way :)
If you run into any problems feel free to open an issue or ping me (
martinklepsch) in the ClojureScript room on Riot.im (no signup required).
The initial release of Tenzing was prompted by the urge to have something like the awesome Chestnut template but built on top of Boot. Many props to Arne Brasseur for making getting started with ClojureScript a lot easier at the time!
Copyright © 2014 Martin Klepsch
Distributed under the Eclipse Public License either version 1.0 or (at your option) any later version.