[Sci-all-l] Asprey Lecture Series: Matthias Felleisen on April 25th, 2007

[Luke Hunsberger]

Matthias Felleisen of Northeastern University will be giving a talk
titled "Typed Scheme" as part of the Asprey Lecture Series on
Wednesday, April 25, 2007 at 4:00 p.m. in Taylor 206.  (Tea will be
served in the Computer Science department lounge at 3:15 p.m.)  Details
are given below and on the Computer Science Department's web site:

	http://www.cs.vassar.edu/

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   Matthias Felleisen, Northeastern University

   "Typed Scheme"

   Time: 4:00 pm

   Date: Wednesday, April 25, 2007
   
   Location: Taylor 206, Vassar College
  
   Note: Tea at 3:15 p.m. in C.S. Dept. Lounge (OLB)


   ABSTRACT

      When scripts in untyped languages grow into large programs,
      maintaining them becomes more difficult. A lack of types means
      that programmers must (re)discover critical pieces of design
      information every time they wish to change a program. This
      analysis step both slows down the maintenance process and may
      even introduce mistakes due to the violation of undiscovered
      invariants.

      This talk presents Typed Scheme, an explicitly typed variant of
      an untyped scripting language, and evidence that the language
      makes it easy to convert scripts into well-typed programs. The
      type system is based on the novel notion of occurrence typing,
      which we formalize and mechanically prove sound. Its
      implementation for the complete programming language borrows
      elements from a wide range of approaches, including recursion
      types, true unions and subtyping, plus polymorphism with a
      modicum of inference. For the validation of the type system and
      its implementation, we report on a number of experiments on
      adding explicit types to a wide range of existing untyped PLT
      Scheme code. These experiments suggest that Typed Scheme
      naturally accommodates the programming style of the underlying
      scripting language.

      Joint work with Sam Tobin-Hochstadt, with help from Ivan Gazeau
     (Ecole Normale Superieure, Paris). 


   ABOUT THE SPEAKER

      Matthias Felleisen is currently a Trustee Professor at
      Northeastern University. He joined its College of Computer and
      Information Science in 2001, after a 14-year career at Rice
      University in Houston with sabbaticals at Carnegie Mellon
      University in Pittsburgh and École Normale Supérieure in
      Paris. He received his PhD from Daniel P. Friedman in 1987.

      Felleisen's research career consists of two distinct 10-year
      periods. For the first ten years, he focused on the semantics of
      programming languages and its applications. His work on
      operational semantics has become one of the standard working
      methods in programming languages. For the second ten years,
      Felleisen and his research group (PLT) developed a novel method
      for teaching introductory programming, including a new approach
      to program design and a programming environment for novice
      programmers (DrScheme). This environment has become a popular
      alternative to the conventional set of teaching tools and is now
      used at a couple of hundred colleges and high schools around the
      world. For Felleisen and his team, the construction of a large,
      realistic software application has posed many interesting and
      challenging research problems in programming languages,
      component programming, software contracts, and software
      engineering.

      Over the past 20 years, Felleisen has published several dozen
      research papers in scientific journals, conferences, and
      magazines. In addition, he has co-authored five books, including
      How to Design Programs and The Little LISPer (now called The
      Little Schemer), which, at the age of 30, is one of the oldest
      continuously published books in the field.