The wiki (https://github.com/ArkScript-lang/Ark/wiki/Embedding#creatin...) calls them “plugins” and they’re also called “modules”, which I think is a lot clearer than “FFI”. Essentially it’s a bunch of native functions that are exported with C linkage and compiled into a set of shared libraries, which are then loaded and the functions in them looked up at runtime. On the other (C++) side it’s similar to e.g. a JNI binding or any other language where you can pull values out of the runtime.