Thanks for the recommendation. I respect LTU-respected language designers. I didn't know it was 15+ years old.
Stop-the-world might be ok for batch compute work where I care about amortized cost (as long as the GC itself could use all my cores efficiently).
I'd be interested in the debugger experience - since it compiles to C++, I'm a little scared.
I think you meant parallelism there. Felix does have preemptive threads for that, but its a relatively new addition, so I expected it to be rough on the edges.
You will probably be able to catch Skaller on LTU, ATS mailing list and of course on Felix's own mailing list. He can answer questions better than I can.
I think you will have to debug the generated C++ because I dont think it preserves the corresponding Felix source lines by default.
The good thing is that it supports functional style (though not restricted to it), so you can debug individual functions easily enough. Besides it has robust and flexible type system (way better than C++'s) that you can enlist to catch errors early. It does type deduction so you dont have to litter the code with types.