[nonsince]

To add another existing implementation of this, Naughty Dog's Lisp-based assembler could do hot code reloading, and that workflow was extensively used for developing Jak & Daxter. Plus, obviously any JIT'd language can do this but it's fair not to count that. Still, that's just splitting hairs and it's really exciting to see this in Nim. It's a great language and it's a shame that it doesn't seem to have found a real niche yet.

http://www.codersnotes.com/notes/disassembling-jak/

[OskarS]

There are many game engines do some form of hot code reloading of the game scripting code (as opposed to engine code). Unity supports it for C#, for instance (though it's finicky, you have to program with hot reloading in mind).

[pjmlp]

And Unreal does it for C++ as well now.