If I'm reading the post correctly, the HN title is inaccurate. The in-progress STM was already written in C. It was the garbage collector that was written in

If I'm reading the post correctly, the HN title is inaccurate. The in-progress STM was already written in C. It was the garbage collector that was written in RPython, and that has been rewritten in C as part of a combined STM/GC library. edit: fixed now.