Generic Haskell project introduction

The goal of the Generic Haskell project is to develop:

a generic programming language extension of Haskell;
practical examples such as a database connection and XML tools;
programming methods for the language extension.

Thus we will obtain a truly generic, type-safe, and practically applicable extension of Haskell.

Generic Programming

Software development often consists of designing a datatype, to which functionality is added. Some functionality is datatype specific, other functionality is defined on almost all datatypes, and only depends on the type structure of the datatype. Examples of generic (or polytypic) functionality defined on almost all datatypes are storing a value in a database, editing a value, comparing two values for equality, pretty-printing a value, etc. A function that works on many datatypes is called a polytypic function.

Since datatypes often change and new datatypes are introduced, we have developed Polyp, an extension of the functional programming language Haskell that supports defining polytypic functions. However, Polyp allows the definition of polytypic functions on a limited set of datatypes, which hinders the wide application of polytypic programming.

Recent work by Hinze shows how to overcome many of the current limitations of Polyp by extending Haskell with a construct for defining type-indexed functions with kind-indexed types. Generic Haskell will be developed based on Hinze's ideas.

Project description

Here is the postcript file with the project proposal. The goal of the Generic Haskell project is to develop:

a generic programming language extension of Haskell. We will write a language report, and a prototype implementing the language as described in the report. The first prototype has been released in November 2001, and since then several new versions have been released.
practical examples such as a database connection. Practical examples of generic programs have been given by Hinze, and Jansson and Jeuring. We will implement some of these examples in the prototype.
programming methods for the language extension. It is sometimes difficult to specify and write generic programs for particular problems. We will develop methods and tools to support the construction of generic programs.

For information contact info@generic-haskell.org