I see two main reasons for this. The first is obviously pg apparent disinterest in his own creature (in the sense that he seems to don't follow the forum anymore), because this makes people think "If its creator doesn't care about it, why should I?". Maybe pg is a bit too busy in this days, but I think Arc is still too young to survive if he doesn't come back soon, beacuse there are a lot of other interesting lisp projects out there that don't give the same sense of 'pause' that Arc gives (clojure is one of them). The second reason is the immature implementation that makes it difficult to write projects of moderate size in Arc, as an example think about Arc's error messages: they usually say something like 'You've got an error' and you simply don't get any hint about where it is. This is especially true about reader errors: I've read messages saying 'error at line 5234' in a file with just a few hundreds lines!
The good news is that these problems are, IMHO, fixable. Think about arc2c and how it is trying to fix the second problem to see the direction where the Arc community should go, but these solutions require time, and new users usually don't want to wait when there are other solutions already usable out there.
"The first is obviously pg apparent disinterest in his own creature..."
I think you hit the nail on the head there. I know pg has said that he does read the posts even when he doesn't reply, but let's face it, it doesn't take too long to post a comment occasionally. If he even took the time to communicate a vision to the "community", that would be helpful. I think people would be more patient if they had a clue about where this was heading.
Although it's certainly fun to pick up a new language, it also takes time and effort, and I'd like to see more evidence that Arc will continue to progress before I invest much time into it (especially since it lacks a couple "must haves" for me currently).
So, regarding the other comment about needing more publicity in terms of someone's pet project - I think there's a catch-22 there - who's going to put together a substantial application if they're unsure if the language will survive?
"who's going to put together a substantial application if they're unsure if the language will survive?"
This is true if you're writing your application for commercial use, but if you're doing it just for fun you can even use a language written by yourself that no one else know. The biggest problem is the lack of development and debugging tools. I few weeks ago I started a project to learn a bit more about compilers, and I ended up using Common Lisp because the task was very difficult by itself and I needed a good way to debug the program. Using Arc would have meant to make a difficult project even more difficult.
I think you just proved my point. I presume your project to "learn a bit more about compilers" was not commercial in nature, and yet you chose Common Lisp. Whether a project is for fun or for profit, I'd prefer to not waste my time, and it appears you feel the same.
I think the survivability (not popularity) of a programming language is closely correlated with its usefulness to programmers.
Of course, the best way to rebut my implicit assertion is to actually "put together a substantial application" with Arc instead of talking about it, right?
However, seriously, clojure looks really interesting, being a cool language on the JVM and being purely functional. But does anybody know if it is possible in this language to make (easily) funny structures like circular lists, graphs, etc. ? AFAIK, that's the problem when you don't want to use set-car & set-cdr in Scheme (that's a problem in NewLisp too, for example) : you loose them. Did clojure manage to overcome this problem ?
