Not only that, we have the Java and .NET runtimes, both of which can be used from many languages. I'd say, along with C, that makes three widely adopted approa

Not only that, we have the Java and .NET runtimes, both of which can be used from many languages. I'd say, along with C, that makes three widely adopted approaches to sharing libraries between languages. Furthermore, C libraries don't even have to be written in C. It's far from unheard-of to use a more powerful language like a lisp or Ocaml to write a C library.