We had something similar quite a while ago at Naughty Dog, when working on the Jak and Daxter PS2 games. Our development environment was Emacs, and as well as having a REPL console in one of the buffers, you could position your cursor inside any function/method, hit CTRL/T, and have just that function compiled and updated on the target hardware, on the fly, with no restart required.
Iterative programming is especially suited for game development, where you want to rapidly experiment with tweaking parameters and behaviors without waiting for a full compile/link/download/restart.
