Since its inception in 1987, Haskell has provided a focal point for research in lazy functional programming. During this time the language has continually evolved, as a result of both theoretical advances and practical experience. Haskell has proved to be a powerful tool for many kinds of programming tasks, and applications in industry are beginning to emerge. The recent definition of Haskell 98 provides a long-awaited stable version of the language, but there are many exciting possibilities for future versions of Haskell.

The fourth Haskell Workshop will be held as part of the PLI 2000 colloquium on Principles, Logics, and Implementations of high-level programming languages in Montreal, 17th September 2000. Previous Haskell Workshops have been held in Paris (1999), Amsterdam (1997) and La Jolla (1995). Following on from these workshops, a special issue of the Journal of Functional Programming will be devoted to Haskell. Possible topics include, but are not limited to:

* Critiques of Haskell 98;

* New proposals for Haskell;

* Applications or case studies;

* Programming techniques;

* Reasoning about programs;

* Semantic issues;

* Pedagogical issues;

* Implementation.

Contributors to any of the Haskell workshops are invited to submit full papers to the special issue on Haskell, but submission is open to everyone. Submissions should be sent to guest editor (address below), with a copy to Nasreen Ahmad (nasreen@dcs.gla.ac.uk). Submitted articles should be sent in postscript format, preferably gzipped and uuencoded. In addition, please send, as plain text, title, abstract, and contact information. The submission deadline is 1st February 2001. For other submission details, please consult an issue of the Journal of Functional Programming or see the Journal's web pages.