Yeah, jank doesn't much with JVM APIs or the JVM at all. We have our own implementation of the compiler and runtime. It has similarities to Clojure's design, only because the object model somewhat demands that.
> Don't implement your own GC, just use mmtk [1].
Yep, already the plan. Currently using Boehm, but MMTK is the next upgrade.
> Don't underestimate complexity and importance of multi-threading and concurrency.
Clojure aids this in having STM, immutable data structures, etc. However, there are some key synchronization points and I do need to audit all of them. jank doesn't have multi-threading support yet, but we will _not_ go the way of Python. jank is Clojure and Clojurists expect sane multi-threading.
> Don't spend too much time benchmarking and optimizing single threaded performance against JVM as performance baseline.
This year, not much optimization has been done at all. I did some necessary benchmarking early on, to aid in some design decisions, but I follow this mantra:
1. Make it work
2. Make it correct
3. Make it fast
I'm currently on step 2 for most of jank. Thanks for sharing the advice!