The Dagstuhl seminar (04381) on Dependently Typed Programming brought together researchers from all over the world who are interested in the use of dependent types in programming. An emerging topic was the interaction of the functional programming community and the Types community: an example is the use of GADTs in Haskell, which represent a restricted use of dependent types in Haskell while on the other hand proof systems like COQ in which allow the expression of many functional programming idioms. Emerging languages and systems, like Epigram, attempt to unify functional programming and Type Theory based proof development environments. Discussions during the seminar centred on the question how to integrate dependent types in real programming languages and on the pragmatic and theoretical questions raised by doing this.

Dependently typed programing changes the way we program in a more fundamental way than immediately obvious - it affects the tools we use (interactive programming, elaboration), the data structures we create and which programs we choose to write. As a consequence the design of languages, tools and programs is an exciting and challenging new topic. The proposed seminar is intended to get language designers, programmers and theoreticians together, discuss the issues arising and compare solutions and prototypical implementations.

This seminar continues the theme of the Dagstuhl Seminar 01341 (Dependent Type Theory meets Practical Programming) in August 2001 and is related to topics in the EU working groups APPSEM and TYPES.