Motivation

The naive workflow for creating code looks like this:

This process isn't very interactive or fun. And as the app gets bigger, the compile step will take more time, and this process becomes very inefficient.

Existing solutions

However, these solutions aren't terrific. First, you are usually limited to how much stuff you can change without needing to recompile. Second, these solutions usually take a lot of programmer effort to set up and maintain.

(And then there is Smalltalk, which solves these problems. However, this language didn't fit my needs, for reasons which are outside the scope of this 5-minute essay.)

So, I wanted to see if I could solve this problem in a better way. I came up with a list of requirements for this dream language.

Requirements

Requirement #1: While running an app, I should be able to modify a source file, reload it, and have the program's state be preserved across the reload (as much as possible).

But then, I also want to change stuff *inside* the program. I want to be able to just click something to change its color, or reposition it, or something else. I also want to have a variety of interfaces for viewing and changing code.

Requirement #2: It should be easy, from an API perspective, to inspect and modify code.

Then came the question, if I modify code at runtime, how do I save those changes? I didn't like the Smalltalk way of saving to an image. I like just using text source code. The world already has a great selection of text editors, source control systems, syntax highlighters, IDEs, and other tools which operate on text files. I don't want to rewrite those.

Requirement #3: We should be able to save modified code back to text, with whitespace and comments all preserved.

The Circa workflow

Which I think works pretty well.

Conclusions

To find out more, click here.

Circa is still a work-in-progress. To see the current status of its implementation, click here.

Thanks for reading!

- Andy