[Pl-seminar] Benjamin Pierce talk at Harvard: April 19, 10:00AM

Allyn Dimock dimock at deas.harvard.edu
Wed, 3 Apr 2002 14:33:03 -0500 (EST)

Benjamin Pierce will be giving a talk at Harvard on Friday, April 19
at 10:00AM in Maxwell-Dworkin G125:

April 19th, 2002
MD G125
Benjamin C. Pierce
University of Pennsylvania



The recent rush to adopt XML can be attributed in part to the hope
that the static typing provided by DTDs (or more sophisticated
mechanisms such as XML-Schema) will improve the robustness of data
exchange and processing.  However, although XML _documents_ can be
checked for conformance with DTDs, current XML processing languages
offer no way of verifying that _programs_ operating on XML structures
will always produce conforming outputs.

In previous work, we have designed and implemented a domain-specific
language for XML processing, called XDuce.  The main novelties of XDuce

  1) A type system based on REGULAR EXPRESSION TYPES.  Regular
     expression types are a natural generalization of DTDs, describing
     structures in XML documents using regular expression operators
     (*, ?, |, etc.) and supporting a powerful form of subtyping.

  2) A corresponding mechanism for REGULAR EXPRESSION PATTERN MATCHING,
     which supports concise "grep-style" patterns for extracting
     information from inside structured sequences.

The lessons learned from XDuce are now being incorporated in a new
language, called Xtatic, whose design focuses on smooth integration of
these novel XML-processing features into mainstream, object-oriented
languages such as C#.  The current vision is that Xtatic will be
engineered as a lightweight extension to C#, offering native support
for regular expression types and patterns and completely interoperable
at the binary level with ordinary C# programs and APIs.

This talk describes the basic design principles of Xtatic, discusses a
few of of the fundamental technical issues in more depth, and sketches
the current state of the project.