XHaskell --- Adding Regular Expression Types to Haskell

We present an extension of Haskell, baptized XHaskell, which combines parametric polymorphism, algebraic data types and type classes found in Haskell with regular expression types, subtyping and regular expression pattern matching found in XDuce. Such an extension proves in particular useful for the type-safe processing of XML data. For example, we can express XQuery and XPath style features via XHaskell combinators. We have implemented the system which can be used in combination with the Glasgow Haskell Compiler.