A small example of refactoring running code is at http://www.youtube.com/watch?v=1kuoS796vNw http://www.youtube.com/watch?v=1kuoS796vNw And a more lengthy exam

A small example of refactoring running code is at http://www.youtube.com/watch?v=1kuoS796vNw http://www.youtube.com/watch?v=1kuoS796vNw And a more lengthy example of writing tests first, letting the code fail, and fixing things in the debugger: http://vimeo.com/19591202 http://vimeo.com/19591202 This is kind of like writing code that doesn't exist or doesn't work, and letting the type checker guide you through the things you need to fill in. The difference is that Smalltalk is actually executing your code, so you can see actual values rather than just type errors, and it will keep trying to execute your code while you change things. It might be possible to do something like that with static typing, but I think the real issue is that most advocates of static typing wouldn't really _want_ to mess around with programs in inconsistent states in the first place.