Does anybody remember Apple Dylan (http://wiki.opendylan.org/wiki/view.dsp?title=Apple%20Dylan)? I never used it myself, but I remember reading a lot about it in the late 1990's because I was using Macintosh Common Lisp at the time. In the Apple Dylan IDE, every function, class, and module was an object in an object database; there were no files at all. The IDE was at least 10 years ahead of its time, and as a result the performance was terrible. But it's surprising that nobody has revived the idea of a source database.