Andrew Wilson Appel (born 1960) is the Eugene Higgins Professor of computer science at Princeton University, New Jersey. He is especially well-known because of his compiler books, the Modern Compiler Implementation in ML (ISBN 0-521-58274-1) series, as well as Compiling With Continuations (ISBN 0-521-41695-7). He is also a major contributor to the Standard ML of New Jersey compiler, along with David MacQueen, John H. Reppy, Matthias Blume and others and one of the authors of Rog-O-Matic.
Appel gained an A.B. summa cum laude (physics) at Princeton University in 1981, and a Ph.D. (computer science) at Carnegie-Mellon University, in 1985. He became an ACM Fellow in 1998.
From July 2005 to July 2006, he was a visiting researcher at the Institut national de recherche en informatique et en automatique (INRIA), Rocquencourt, France, on sabbatical from Princeton.
Andrew Appel campaigns on issues related to the interaction of law and computer technology. He testified in the penalty phase of the Microsoft antitrust case in 2002. He is opposed to the introduction of some computerized voting machines, which he deemed untrustworthy. In 2007, he received attention when he purchased a number of voting machines for the purpose of investigating their security.
In 1981, Appel developed a better approach to the n-body problem in linearithmic instead of quadratic time.
Andrew Appel is the son of noteworthy mathematician Kenneth Appel, who proved the Four-Color Theorem in 1976.