Personally I find that the 'killer feature' is Racket integration as Racket has quite an extensive well-documented standard library (and FFI so that's all C libraries as well).
Even if Arc doesn't get much attention itself, it still benefits from the work going into Racket.
So there are a lot of libraries available. (Arc's Racket integration still has a few rough edges, particularly regarding keyword arguments, but there are workarounds.)
That doesn't really qualify as a 'killer feature' for Arc; it doesn't provide any incentive for someone to learn and use Arc - and keep using it - over just learning Racket in the first place.
I do agree that it dramatically improves the value of Arc over being written as a stand-alone interpreter. And providing easier access to Racket features may be a good idea. It helps bootstrap Arc, like Clojure on the JVM with the Java standard libraries until proper clj wrappers are written.
I think it is a killer feature in a round-about way. I believe the killer feature is actually generic and robust database integration. There's a whole lot of people who start with data on hand and need to hack together an app from there. The starting point to db integration is racket, which also gets you access to other libraries. Once in place arc libs can be created eliminating a need to even learn racket (just like there are plenty of clojure programmers who don't know java).
IMO doing package integration first is putting the cart before the horse.
> the killer feature is actually generic and robust database integration
That could be a killer feature, but I don't think we have it developed yet. I certainly wouldn't have thought of it. Basically, when I say "killer feature", I'm thinking of the specialization or distinguishing characteristic that we would emphasize in a Quick Start tutorial.
When arc was first launched, the "arc challenge" of building a multi-action website with a form in only ~5 lines of code was the "special feature." Right now, I think hackability and simplicity of the syntax are two of the better things, but we could probably specialize on more.
> IMO doing package integration first is putting the cart before the horse
The purpose for working on package integration is to enable further development. Without the ability to share code easily, it's a lot harder to build on and benefit from community effort. In itself, I agree, a package manager is boring and probably not a killer feature. However, making it really easy to start building something useful by searching for and loading relevant code straight from the interactive console would be a pretty big step.
Perhaps the specialty I'm looking for is exploratory programming, which we've mentioned before. Our interactive help system is pretty good. The only problem others have mentioned before was that Python is arguably better, just because there are already examples and libraries for doing most activities, whereas Arc requires a lot of development effort just to get fundamental components working.
Well there's that, but honestly... exploratory programming with a tool that can't provide basic functionality will limit how much you can explore. I think you mean 'language design exploration'? - if so I'll stop right there, since, well, frankly... it's not my wheelhouse. :)
> package integration first is putting the cart before the horse
I'm simply saying that features like db integration bring users, users bring manpower, manpower will provide package management in a way that ensures it accounts for more use cases, but again this is moot if what you're interested in is only the language development arena. Though I'm not sure how you could prove out a language unless you can actually use it for real world work.
P.S. If you want users, then killer feature would = todo list mobile app with local db in 30 lines of code!
> exploratory programming with a tool that can't provide basic functionality will limit how much you can explore
Absolutely true, which is why I do think the Racket integration is important, so we can just wrap its many and powerful libraries in lighter-weight arc libs, and also why I think a decent package system is important. It needs to be easy to share code, and to find solutions to problems. Otherwise everyone spends too much time rebuilding the same wheels.
> features like db integration bring users
Absolutely. I think better db support in arc would be awesome to have. Especially if we can build an ecosystem where "intelligent defaults" are the norm, so that 90% of the time the exploratory developer can get a db up and running with 1-2 lines.
> todo list mobile app with local db in 30 lines of code
An admirable goal. That's actually a great idea of something we could work toward as a community project, each building pieces that eventually come together to make a decent modern app.
Were you thinking a mobile friendly web app, or trying to run it natively on a phone? I'm not really sure how the latter would work... Though building a compatible javascript base for arc would be pretty nice. I do like being able to use consistent code for both clients and servers, as in node and clojure.
> Were you thinking a mobile friendly web app, or trying to run it natively on a phone?
The java/js ecosystem has the largest reach making it the easy choice. One could work on a js compiler and target pouchDB as a starting point. That said choosing js also makes Arc go further down the path Clojure has already gone putting the two closer together, and with Clojure being so far ahead in that arena then maybe it's doomed to fail. The other way to go is to do what Clojure is not great at. iOS development? maybe integration with swift? At any rate I'm not a language development guy. I can only tell you what would appeal to me. I mostly use Clojure and a really easy to use arc->iOS app development ecosystem would be really cool.
> Without the ability to share code easily, it's a lot harder to build on and benefit from community effort.
I've just been dumping my Arc experiments into the Anarki repository. Akkartik manages it by the policy that pretty much anyone can commit anything, so I haven't had any issues sharing my code. I've recently put a Puredata compiler in Arc in there, https://github.com/arclanguage/anarki/blob/master/lib/pd.arc
The interactive help in Anarki is great, although there are some undocumented functions. A great improvement, which would be very easy to implement, would be to add the documentation from the various Arc sites to the Anarki interactive help.
I do know some Racket, and for me this exact feature did provide an incentive for me to learn and use Arc, because I could apply what I already knew.
Arc feels more brief and less strict, so in some cases it's more pleasant to use than Racket.
When I found out about Arc's Racket interop a couple of years ago, I was really surprised that this was not documented anywhere, so I added a section in the Readme.
I agree it's important, and we should probably develop it and make it easier because it's an important foundation. However, there aren't that many Racket developers, and its not really the best argument in favor of using a language that it just happens to be a better version of another language. That might be a competitive advantage against Racket, but what about compared to other interpreted languages? Why would someone want to use arc over Python or Ruby?
> When I found out about Arc's Racket interop a couple of years ago, I was really surprised that this was not documented anywhere, so I added a section in the Readme.
Yeah, the documentation could use some work. Definitely not our competitive advantage at the moment, though that could be changed if we build on our interactive help system.
Also, that feature is really only part of anarki. I don't think arc3.1 had that feature. I think at this point it seems like pg has pretty well abandoned arc though, so maintaining compatibility shouldn't be a primary concern.
Hmm, I don't think pg has abandoned Arc. And I don't think maintaining compatibility is a concern even so. So far Arc has made no compatibility guarantees. We're all forking pre-alpha software. So it's conceivable the hundred-year language will have features from Anarki. Forks that restrict where they get good ideas from will be outcompeted by forks that don't.
Though lately I consider it more likely that a hundred-year language will have a leveled-up conception of "compatiblity", one that assumes orders of magnitude more forking activity. (See "the Zen of Mu" at the bottom of http://akkartik.github.io/mu; Mu is my attempt at building out the foundations for a hundred-year stack. With, perchance, something like Arc on top.) Perhaps Arc shouldn't be a single language but a family of forks (https://lobste.rs/s/n0d3qo#c_rue8pf). Not a single tree but a clonal colony (https://en.wikipedia.org/wiki/List_of_longest-living_organis...). That'll only work if we can make it easy for superficially-incompatible forks to exchange features and functionality back and forth. Which is an unsolved problem so far. So we may well be very far from a hundred-year language.
Anyways, this tangent is my contribution. I don't have a short-term answer for how to solve Arc's users-vs-libraries chicken-and-egg problem ^_^
> I don't have a short-term answer for how to solve Arc's users-vs-libraries chicken-and-egg problem ^_^
Be the change you want to see in the world... I'm not really sure how to motivate the community, but I am rather attached to it, even if I have been a very infrequent lurker over the past years. We have had a relatively high amount of discussion over the past few days though...
I don't think we can just expect to flip a switch and suddenly get a community; we have to /be/ a community, and then people might be willing to join us.
Maybe we should emphasize the flexibility of our language designs by making the language itself more modular. It would be challenging from a compatibility/dependency standpoint, but those are problems we might have to solve anyway. It would help to have better isolation of components.
It looks like I might've subtly broken ns.arc with my own changes to make Anarki installable as a Racket package. Here's an example that should be working, but currently isn't:
; my-file.arc
(= n 2)
(= my-definition (* n n))
arc>
(= my-definition
(let my-ns (nsobj)
; Populate the namespace with the current namespace's bindings.
(each k (ns-keys current-ns)
; Racket has a variable called _ that raises an error when
; used as an expression, and it looks like an Arc variable, so
; we skip it. This is a hack. Maybe it's time to change how
; the Arc namespace works. On the other hand, copying
; namespaces in this naive way is prone to this kind of
; problem, so perhaps it's this technique that should be
; changed.
(unless (is k '||)
(= my-ns.k current-ns.k)))
; Load the file.
(w/current-ns my-ns (load "my-file.arc"))
; Get the specific things you want out of the namespace.
my-ns!my-definition))
4
arc> n
_n: undefined;
cannot reference an identifier before its definition
in module: "/home/nia/mine/drive/repo/mine/prog/repo/not-mine/anarki/ac.rkt"
context...:
/home/nia/mine/drive/repo/mine/prog/repo/not-mine/anarki/ac.rkt:1269:4
The idea is, you create an empty Arc namespace with (nsobj), you use `w/current-ns` to load a file into it, and you use `a!b` or `a.b` syntax to manipulate individual entries.
An "Arc namespace" is just a convenience wrapper over a Racket namespace that automatically converts between Arc variables `foo` and their corresponding Racket variables `_foo`.
For some overall background...
I wrote ns.arc when I didn't have much idea what Racket namespaces or modules could do, but I was at least sure that changing the compiled Arc code to more seamlessly interact with Racket's `current-namespace` would open up ways to load Arc libraries without them clobbering each other. It wouldn't be perfect because of things like unhygienic macros, but it seemed like a step in the right direction.
I went a little overboard with the idea that Racket namespaces and Racket modules could be manipulated like Arc tables. However, that was the only clear vision I had when I embarked on writing the ns.arc library, so I approximated it as well as I could anyway. In fact, I don't think the utilities for generating first-class modules (like `simple-mod` and `make-modecule`) are all that useful, because as I understand a little better now, Racket modules are as complicated as they are mainly to support separate compilation, so generating them at run time doesn't make much sense.
I'm still finding out new things about what these can do, though. Something I didn't piece together until just now was that Racket has a Racket has a `current-module-name-resolver` parameter which can let you run arbitrary code in response to a top-level (require ...) form. I presume this would let you keep track of all the modules required this way so you can `namespace-attach-module` them to another namespace later. Using this, the kind of hackish partial-namespace-copying technique I illustrate above can probably be made into something pretty robust after all, as long as Anarki sets `current-module-name-resolver` to something specific and no other code ever changes it. :-p
I tinkered with Anarki a whole bunch and finally got this working smoothly. There was a missing step, because it turns out we need to load certain Racket-side bindings into a namespace in order to be able to evaluate Arc code there. It seems more obvious in hindsight. :)
I approached this with the secondary goal of letting a Racket program (or a determined Arc program) instantiate multiple independent intances of Anarki. The ac.rkt module was the only place we were performing side effects when a Racket module was visited, and Racket's caching of modules makes it hard to repeat those side effects on demand, so I moved most of them into a procedure called `anarki-init`.
By adding one line to the example I gave...
(= my-definition
(let my-ns (nsobj)
; Load the Arc builtins into the namespace so we can evaluate
; code.
(w/current-ns my-ns ($.anarki-init))
...))
...it becomes possible to evaluate Arc code in that namespace, and the example works.
Before I started on that, I did a bunch of cleanup to get the Anarki unit tests and entrypoints running smoothly on all our CI platforms. To get started on this cleanup, I had a few questions hjek and akkartik were able to discuss with me on issue #94: https://github.com/arclanguage/anarki/issues/94
A lot of the problems I'm fixing here are ones I created, so it's a little embarrassing. :) It's nice to finally put in some of this missing work, though. I want to say thanks to shader and hjek for talking about modules and packages, provoking me to work on this stuff!
