Holy grail

Well, on second thought, let’s not go to Camelot – it is a silly place. — King Arthur

What is it?

This demonstrates the holy grail workflow for web development the way I envision it: an auto-restartable back-end in the REPL + a hot-reloadable front-end in the browser.

This workflow is built on top of Boot, a build tool, and system, a component library.

Requirements

1. `boot`
2. Datomic

Installation

Clone this repo, `cd` into it, and start the development pipeline build.

$ git clone git@github.com:Hendrick/holygrail.git
$ cd holygrail
$ boot dev

Testing

To test:

$ boot test

What’s Happening

`boot dev` runs the following tasks:

1. Sets up environment variables with `environ`
2. Creates a file watcher
3. Creates a `dev-system` that reloads when `handler.clj` changes
4. Sets up to reload when you change a `cljs` file
5. Sets up `cljs` compliation
6. Sets up a REPL
7. Ensures that your Datomic schema is transacted
8. Seeds your Datomic database

Things TODO

• Task to autodownload Datomic if it’s not installed locally?
• Investigate option to not seed on every change
• Use datascript for client-side
• Add devcards!

Principle of operation

Manual

You want to operate with a REPL, start the system, and reset it when you make changes.

Compose a build pipeline:

(deftask dev
  "Run a restartable system in the Repl"
  []
  (comp
   (environ :env {:http-port 3000})
   (watch)
   (system :sys #'dev-system)
   (reload)
   (cljs)
   (repl :server true)))

Start it:

$ boot dev

Pay attention to the line that says:

nREPL server started on port 49722 on host 127.0.0.1 - nrepl://127.0.0.1:49722

Launch your favorite editor, and connect to the headless REPL (M-x cider-connect in Emacs works great). Then type:

(go)

Your web app is started and listening at http://localhost:3000. When you make changes that require a system restart, type in the REPL:

(reset)

Automatic

The boot-system task allows you to automate all of the above.

(system :sys #'dev-system :auto-start true :hot-reload true :files ["handler.clj"])

The auto-start option takes care of starting the app the first time. Your system will automatically be reset after editing handler.clj. Changes elsewhere do not require a system restart, and are available via namespace reloading everytime you save your work.

Note: The build.boot in this repo already contains those options.

Demo

A demo video that tries to demonstrate how developing for the web can be a liberating and seamless experience.

Do you feel the creative juices flow? Are you ready for endless hours of sheer creative output?