Allegro Common Lisp is a full ANSI Common Lisp implementation. It contains many extensions, including 32- and 64-bit native compilation, efficient built-in memory management, foreign functions , multiprocessing, UNICODE and locale support, XML/HTML parsers, a Web client and server, GTK+ interface (

Allegro Common Lisp is a variant of the Common Lisp programming language developed by Franz Inc. It generally includes an implementation of Prolog.