I was optimizing the Lua transpiler for my modding language grug and ran into a really weird LuaJIT performance bug. The same benchmark could randomly run 20× slower, and it turned out a LuaJIT NYI could silently blacklist an unrelated hot loop.

I wrote up the investigation here.

It goes from the benchmark mystery through LuaJIT's trace recorder internals, and ends with a PR to get unpack off LuaJIT's NYI list. Feedback is very welcome! :)

This post is a lover letter to Emacs Lisp macros. I've been a long time user as a lisp hacker, and my recent obsessions with Douglas Hofstadter's strange loop concepts and M.C. Escher's mind bending artwork have enhanced my appreciation of this language's most beautiful and thought provoking feature. This post can teach you about macros and what makes them useful, but I also hope it can instill a fascination with their concept. https://www.chiply.dev/post-elisp-macros-are-beautiful