A small dialect of Common Lisp based upon lisp500
Lisp5000 is based on Teemu Kalvas's lisp500. Lisp5000 is an attempt to document and clean up the original Lisp500 source code to make it more useful for teaching and hacking.
The name Lisp5000 is something of a joke. The original Lisp500 attempted to fit everything in 500 lines of uncommented, densely formatted C code. Once the Lisp500 code is formatted and commented it's expected to grow to closer to 5000 lines in length.