Troels Henriksen writes:
I think they are just as useful as comments to the person reading the code. I'm not a fan of (SETF DOCUMENTATION), as it separates the documentation from the code, making it easier for the two to get out of sync.
I would agree for projects where the spec evolves rapidly and the code with it. For projects with a relatively stable spec like CLIM or CL itself, I find the docstrings distracting. I mean, if you read the code for CAR, do you really find it useful to see the docstring?