This is an implementation of an infix reader macro. It should run in any valid Common Lisp and has been tested in Allegro CL 4.1, Lucid CL 4.0.1, MCL 2.0 and CMU CL. It allows the user to type arithmetic expressions in the traditional way (e.g., 1+2) when writing Lisp programs instead of using the normal Lisp syntax (e.g., (+ 1 2)). It is not intended to be a full replacement for the normal Lisp syntax. It is known to be compatible with CMUCL, CLISP, MCL, and SBCL. Written by Mark Kantrowitz, School of Computer Science, Carnegie Mellon University, March 1993. WWW: http://www.cliki.net/infix