Crosscut

The idea of immediacy, that you make a change and see the result in your program without delay, that's the central premise Crosscut. This is expressed as interactive programming. And yet, I started the previous prototype without that feature. Based on experiences in an even earlier prototype, I had considered that a solved problem, to the limited extent that it had been relevant so far.

And that was a mistake. I implemented interactive programming later, as an afterthought, and it ended up not working very well. It was missing the features required to make it work well with the language that had developed up to that point. And on top of that, the earlier prototyping had been more limited than I had realized, which caused problems of its own.

Such a central feature must be there from the beginning. Everything else that is being added, needs to adapt to it. Then I can keep it working all the way through, as the language grows around it. The new prototype is starting out with exactly that premise.