>One approach to development in CL is to evaluate a form you would like to have. You end up in the debugger. You write the implementation until the error goes away.

This doesn't sound very sustainable or effective to me... almost all the bugs I encounter in programming are algorithmic in nature. The code compiles without error and runs without crashing, but it just happens to do X instead of Y. The code fails because I didn't understand the problem well enough. That's one thing that computers can't really help with yet.