[patrickmay]

> What kind of programs can work like that? Continuously running programs, like web servers/GUI programs?

I use Common Lisp and Hunchentoot to build RESTful web applications. I can connect to the Lisp image running on the server using Swank from Emacs on my development box. If there is a bug, I can change the function, recompile it, and test the change with curl, without rebooting the server or reloading the app. The same techniques work for adding new functionality and APIs.

I suggest just giving it a try. It'll change the way you think about building systems.

[tomp]

What do you do then, after successfully fixing the bug? Are the changes automatically reflected in files, or do you need to manually perform the same change locally and commit it, so that it's there when the server is next redeployed?