[Aardappel]

All the VM runtime functions are written in C++, as are all of the built-in functionality and the engine it uses. To use C, either all of that needs to be rewritten in C, or there needs to be a clear layer between the two, but the API surface is fairly big.

It actually uses C for the JIT (libtcc), but the fact it has to go thru a layer is a source of slowness and complication.