Warren was born in Philadelphia, PA and grew up in Miami, FL. He attended the California Institute of Technology, graduating with a BS in Mathematics, in an age before there were computer science degrees. He completed his education at the Massachusetts Institute of Technology, under the guidance of his thesis advisor Marvin Minsky. In his Ph.D. thesis, Warren described his program PILOT, which contained the first implementation of the concept of "Advice." He invented or created the first implementation of UNDO/REDO, HISTORY, automatic spelling correction, on-line help systems, client-server window systems, multiple overlapping windows, online-help and tools for setting defaults and preferences.

Warren thought of himself as a "graybeard" in the field of computer science, beginning his work before the invention of many concepts that we today take for granted. His most significant work was in the area of making computers easier to use.  His better known works included DWIM (Do What I Mean) and InterLISP. He was awarded the ACM Software System Award in 1992 for his pioneering work in programming environments, as the architect of the InterLISP system, in collaboration with Daniel G. Bobrow, Richard R. Burton, L. Peter Deutsch, Ronald M. Kaplan and Larry Masinter.

Warren worked in the computer science industry for 43 years, contributing to such companies as Bolt, Beranek and Newman, Xerox PARC, Sun Microsystems, and Google. He was an outspoken and colorful character, unafraid of voicing controversial opinions, whether he was contradicting Edsger Dijkstra or Butler Lampson. After retiring in 2011, he collected his experiences in an autobiography with the working title, "Memoirs of a Geek." He was in negotiations with a major publishing company at the time of his death. The company is continuing to pursue the project. For many years Warren coached youth soccer teams in Palo Alto and Mountain View, CA.

During the last part of his life, Warren turned the full force of his enthusiasm and energy to the world of dog agility competition. He loved the sport for its combination of physical and intellectual challenge and the partnership he developed with his Australian Shepherds ("Aussies") Zayvee and Pirate. Warren loved being recognized as "Head-band Aussie Guy," by people who might not have known his name, but could see his love for the sport and for dogs.

Family

Warren was the son of Harry Teitelman, an attorney, and Mynette Bayer, a teacher. He is survived by his wife, Deborah, his sister Paula, nieces, nephews and step-children, and by his dogs, Zayvee and Pirate.