I think my top three language picks would be: C++, Python, and probably Scheme. It really comes down to the cathedral and the bazaar.
Even though C++ and Python have commities, Python has an exposed ast and is probably the most popular language. So it is like going to the bazaar. You can find really anything there. C++ has inline assembly and many weird hacks. A large chunk of it is just undefined behavoir. And, a lot of programming paradigms can go and set up shop in C++. Many other languages say they have a unique quirk, only for it to end up in Python and C++ a few years later.
Languages that tell you what to do are cathedrals. Scheme languages have their 9 primitive functions (9 holy primitives) and that is about it to be a scheme. Their committee tries to make RSR7 do everything. But so few of the older schemers actually care.
@jmw150 a large chunk of any software is undefined behavior, it's just what happens when you break an invariant. The reason c++ has a lot of it in it's spec is because it tries to convey the invariants of the underlying tech (be that the OS, the compiler or the hardware) in some generic fashion. Aside from some historical baggage, these things usually manifest themselves in one way or the other, even if you sweep them under the rug.
