Janus from First Principles§

The goal of this section is to provide a deep understanding of how each piece of Janus works, down to some measure of the internals. There are a few reasons we wish to do this:

1. We want to de-magick the framework. We want it to feel elementary and approachable.
2. We want to instill a sense of the philosophy behind the framework so that newcomers to a more functionally-oriented way of problem solving have some foundation to start from.
3. We want to lay bare the separate pieces so that you better understand how you might leverage them individually in your own work.
4. We want to provide you with the knowledge you need to augment and customize the framework to best suit your own needs.

This may sound dry or needless or excessive: a guide to Rails does not include a deep dive into the internals of ActiveRecord, nor does a jQuery introduction cover the vagaries of its internal selection management.

Our view is that Janus is actually just a collection of very simple functional primitives that we happen to have imbued with some default that make them collectively a potent user interface framework. The more general purpose a tool, the broader its possibility space and so the deeper the understanding it takes to use it to its fullest potential: we are not surprised that even the simplest programming languages require some amount of theoretical study before they may be properly used.

It is very definitely possible to leverage Janus by copy-and-paste incantation work. We think it's still an effective tool used this way. But we hope you stick with this first principles overview, and we promise to keep it as brief and as interesting as we can.

A Note About the Samples in this Section§

In most of the Janus documentation, including all the First Principles articles, we automatically import all members of the janus package into the local scope, along with some basics like jQuery $. This is to cut down on boilerplate noise in the samples.

So any time you see some function or class get used out of thin air, it is something you can import from the janus package. In an actual application, you'll want to require these objects yourself.

Next Up§

The first chapter in this series defines some goals of the framework, which are then used in the subsequent chapter in the course of rederiving the basics of Janus from scratch.