The PLAtform NEutral Transpiler, when combined with mescc-tools; allows one to compile a subset of the C language into working binaries with introspective steps inbetween.
A lovely set of examples of M2-Planet programs are in tests but the most surprising part of all M2-Planet can self-host M2-Planet.
Further more M2-Planet is cross-platform and self-hosting across platforms with fully deterministic builds enabling perfect reproducibility.