[tresta]

I must say that this is a very interesting project. Any hope for an android version?

The problem with making a editor that enforces "correct" coding is how to make the transitional writing work. At least for me, I tend to write things that wouldn't work, jump to some other place and fix up some related issue, and then jump back to where I was to finish that fragment. If you only allow "correct" code that wouldn't work. Also, saving code that is in a half-finished state might be an issue.

Marking the offending s-expressions, though... that would be a neat feature.

[steeleduncan]

Android (like other languages) is on the roadmap once the iPad scheme version is working smoothly.

Your point about the intermediate state between a blank file and working program is true, but for example in TouchScheme you could never have a simple parentheses mismatch error such as (display (+ 1 2) as it takes care of that part of the S Expression for you. This does not however sacrifice any flexibility in what you can write.

[tresta]

> Android (like other languages) is on the roadmap once the iPad scheme version is working smoothly.

Cool, I guess I'll just have to be patient then...

> Your point about the intermediate state between a blank file and working program is true, but for example in TouchScheme you could never have a simple parentheses mismatch error such as (display (+ 1 2) as it takes care of that part of the S Expression for you. This does not however sacrifice any flexibility in what you can write.

Yes, that's true. But the grand-grand-parent wasn't only talking about such simplistic error-checking. At least that was my impression. Say that you were to start writing a lambda expression, and then realize that you need to change something else:

  (lambda (x

With automagic paren-balancing you'd get

  (lambda (x))

which is still an invalid form. You could make the editor auto-insert a nil (or is it #f in scheme? I always get those mixed up), but that would be a dangerous route to take. Or you could mark it as an invalid form and make the user fix it before the editor even considers evaluating the program (or just that fragment).

That said, you have a very interesting program and the ideas I see here are very interesting as well. I hope that you plan to post more updates on this to hacker news!

[steeleduncan]

The scheme equivalent of nil is ill-defined and differs between implementations, though I certainly don't intend to go that route.

In a future post I will attempt to explain TouchScheme's behaviour in this sort of situation more fully, I think I have a good compromise. If you do have an iPad though, please get in touch, I'd love to hear your feedback on the beta.