Apart from C++, which non-toy languages have direct or easy-to-use compatibility to C? As in "I can take a C library out there, and compile my code against it without having to find, write, or configure some kind of wrapper."
I know that lots of languages have compatibility with C through some form of external call or binding (I've been using bindings in Java, Ruby, Python, etc., so I know it can be done). But you rely on someone (possibly you), to write and maintains a binding for all the libraries you want to use, and the binding has to works on all platforms, etc.
Do more expressive languages than C++ have this feature?
Thanks to all for the mentions of swig or related wrapper-generation tools. I am aware that those exists, but I don't think they're really as easy as C->C++ integration... but then integrating with C might be the only thing that is easier in C++ ;) )