Stephanie Weirich

Associate Professor of Computer and Information Science
School of Engineering and Applied Science
University of Pennsylvania

Ph.D. (2002) Computer Science
Cornell University

fax: 215.898.0587
email: sweirich at
office: 510 Levine Hall

Spring 2015 office hours: TBA
Appointment availability

Undergraduate Curriculum: If you have questions regarding Penn's undergraduate programs in Computer Science, send email to .

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News and recent activities

Research Projects

  • Type-directed programming: Defining functions via type information cuts down on boilerplate programming as many operations may be defined once, for all types of data. With my student Brent Yorgey and collaborator Tim Sheard (Portland State), I developed Unbound, a Haskell library for declaratively specifying binding structure and automatically generating free variable, alpha-equivalence and substitution functions. This library is built using RepLib, an expressive library that I developed for generic programming in Haskell. My student Chris Casinghino and I explored arity and type generic programming in Agda, lecture notes from the Spring School on Generic and Indexed Programming provide a gentle introduction.

  • Machine assistance for programming languages research:  Designing and proving properties about programming languages is hard, but the proofs themselves are straightforward once you know how to set them up. At the same time, it is all too easy to miss the one little case that ruins the whole "proof". Modern proof assistants, such as Twelf, Coq, and Isabelle are good at expressing this sort of reasoning, but it is hard to know where to start. I've been working with the POPLmark team to issue challenge problems, organize a workshop, explore techniques for reasoning about binding, and develop educational materials about mechanizing programming language metatheory. Brian Aydemir developed a library for programming language metatheory (used in the Penn tutorials) and LNgen, a tool for automatically proving properties about binding.

Current Ph. D. Students

PhD Graduates

Recent Courses

Contact Information

postal mail:
School of Engineering and Applied Science
Department of Computer and Information Science
Levine Hall
3330 Walnut Street
Philadelphia, PA 19104-6389