There's a community version of the language being developed here: https://github.com/arclanguage/anarki
It works with the latest Racket versions and includes a HN clone. You can see it running here: http://arclanguage.org/forum
It's true that pg isn't working on it though. I wonder if he's ever getting back to it.
Re:Chez Scheme as the Racket VM
by JoelMcCracken on Thursday February 16, 2017 @02:21PM
(#13662735)
I'm not sure if its super important that PG gets back to it. To be honest, I'd love if someone made a summary of what, in 2017, makes arc unique and worth looking into.
FWIW Racket has two types of cons cells: mutable and immutable. And if you know what you are doing - then you can abuse the FFI to mutate the immutable ones (but don't tell anyone) using unsafe-set-mcar! and unsafe-set-mcdr!.
Not sure if that's still true, but AFAIK all work on arc has been stalled for quite a while.