IMH and unqualified O, I think that what holds back widespread Arc adoption (other than the existence of Clojure) are lack of effective namespacing and unhygienic macros, which make modular code and things like proper package management/libraries infeasible if not impossible. Also, the way the dependencies in news are engineered make it very difficult to disentangle or update what has become an obsolescent web application from the core language without risking breaking everyone else's code.
Ironically I've found (others may feel differently) that while pg may have wanted the purpose of Arc to be exploratory programming, he seems to have done so with a number of his own assumptions baked in to the language, implicitly limiting exploration to what he considers to be correct, and to what correlates with his personal style. It's like Arc is Henry Ford's Model T: you can have it in any color you like, as long as you like black.
But changing these aspects of Arc would make it no longer Arc, at least philosophically.
I agree with some of your first point, but the second not so much. I think pg released arc as a first cut with one application baked in to act as marker for a stable version. Obviously I can only guess, but I also think he expected a larger community of interest, one that could take it to the next level. That never happened and with only a handful of keeners, 10 years later, the things you mention in your first point are non-existent or half-baked experiments. It's possible Arc may get there, and I hope it does, but at this rate it may take a hundred years. :)
More interestingly, though, shawn is bringing some interest back (at least for me) and making substantial changes that could breathe new life into Arc. I don't agree with the empty list - nil change, but the table changes and reader changes are good. I do think the more seamless the racket interop is and the more racket can be leveraged, the better. Clojure has good interop with java and that's what made Clojure explosive. If we can do that with Arc/Racket then we are better off for it.
"Clojure has good interop with java and that's what made Clojure explosive. If we can do that with Arc/Racket then we are better off for it."
Do we ever expect Anarki values to be somehow better than Racket values are? If so, then they shouldn't be the same values. (The occasional "interop headaches" are a symptom of Anarki values being more interchangeable with Racket values than they should be, giving people false hope that they'll be interchangeable all the time.)
I think this is why Arc originally tossed out Racket's macro system, its structure type system, and its module system. Arc macros, values, and libraries could potentially be better than Racket's, somehow, someday. If they didn't already have a better module system in mind, then maybe they were just optimistic that experimentation would get them there.
Maybe that's a failed experiment, especially in Anarki where we've had years to form consensus on better systems than Racket's, and aligning the language with Racket is for the best.
But I have a related but different experience with Cene; I have more concrete reasons to break interop there.
IMO, It would be better if arc had implicit methods that provide access to racket capabilities. In Clojure having libraries, name spaces, and a seamless interfaces to java translated into a plethora of libraries for Clojurians to utilize. Can we not do the same? Well if the goal is for "widespread adoption" then we need to.
Isn't Common Lisp a language with a package system and unhygienic macros?
Common Lisp's approach is that the way a symbol is read incorporates information about the current namespace. That way usually all symbols, even quoted ones, can only have collisions if they have collisions within the same file, and this makes hygiene problems easier to debug on a per-file basis.
I don't think it's my favorite approach, but it could very well be a viable approach for Arc. I was using an approach somewhat like this in Lathe's namespace system, although instead of qualifying symbols at read time, I was qualifying each of them individually as needed, using Arc macros.
Good question, but ns.arc manipulates what Racket calls namespaces, which are data structures that carry certain state and variable bindings we might usually think of as "global," particularly the definitions of top-level variables.
What Common Lisp and Clojure call namespaces are like prefixes that get prepended to every symbol in a file, changing them from unqualified names into qualified names.
I think namespaces are a fine approach for Arc. If Anarki's going to have both, it's probably best to rename Anarki's interactions with Racket namespaces (like in ns.arc) so they're called "environments" or something, to reduce confusion. I think they will essentially fit the role of what Common Lisp calls environments.
Of course, people doing Racket interop will still need to know they're called namespaces on the Racket side. Is there another name we can use for Common Lisp style namespaces? "Qualifications" seems like it could work.