Abstract: "CMU Common Lisp is an implementation of Common Lisp that currently runs under Mach, a Berkeley Unix 4.3 binary compatible operating system. CMU Common Lisp is currently supported on MIPS-processor DECstations, Sparc-based workstations from Sun and the IBM RT PC, and other ports are planned. The largest single part of this document describes the Python compiler and the programming styles and techniques that the compiler encourages. The rest of the document describes extensions and the implementation dependent choices made in developing this implementation of Common Lisp.We have added several extensions, including the proposed error system, a source level debugger, an interface to Mach system calls, a foreign function call interface, support for interprocess communication and remote procedure call, and other features that provide a good environment for developing Lisp code."