[grishka]

In many languages you need to somehow define the symbols you import before the linker comes into play. How would you define Swift symbols for C++? For Java? For Rust? And that's provided their linkers would actually know what the Swift ABI is — and they most probably don't. So I guess your only option would be to descend all the way down to assembly and shove the right things into the right registers and then jump to the right place.