CMUCL

CMUCL, short for Carnegie Mellon University Common Lisp, is a free, high-performance implementation of ANSI Common Lisp. It provides a complete development environment, including an optimizing native-code compiler, a runtime system, an interactive debugger, and a large set of libraries. CMUCL aims to be fully compliant with ANSI Common Lisp while offering extensions, and it emphasizes speed and robust runtime behavior.

The project originated at Carnegie Mellon University in the late 1980s and became one of the leading Lisp implementations for Unix-like systems. It contributed innovations in the compiler and runtime that influenced later systems. Development continued through the 1990s, and the CMUCL codebase served as a primary source for the SBCL project, which forked off as a separate implementation and has continued to evolve.

CMUCL runs on various Unix-like platforms, including Linux and BSD variants; Windows support has generally been limited or achieved via ports by third parties. As an open-source project, CMUCL was released under a license compatible with free software distribution.

Today, CMUCL is largely of historical and educational interest within the Lisp community. It is frequently cited for its role in advancing optimizing compilers for Lisp and serves as a reference point for later high-performance Common Lisp implementations such as SBCL.