||This biographical article needs additional citations for verification. (March 2012)|
While in high school, he saw output from one of the "guess the animal" pseudo-artificial intelligence games then popular. He considered implementing a version of the program in BASIC, but once at MIT, he instead implemented it in several dialects of Lisp, including Maclisp.
He was a technical contributor to X3J13, the ANSI subcommittee that standardized Common Lisp and contributed to the design of the programming language. He prepared the document that became ANSI Common Lisp, the Common Lisp HyperSpec (a hypertext conversion of the standard), and the document that became ISO ISLISP. He can often be found on the Usenet newsgroup comp.lang.lisp,  where he contributes not only expertise in Lisp and computer programming, but also an authoritative perspective on Lisp's evolution and Common Lisp's standardization. In some posts there, he has expressed his opinion on open-source software, including open source implementations of Lisp and Scheme, as something that should be judged individually on its essential merits, rather than automatically considered good merely by the fact of being free or open.