Haskell 98 is a pure functional programming language, and is my language of choice for pretty much any application. There is much information about Haskell on the Haskell website; these pages contain just a few odd snippets that I've written.
I am writing a tutorial entitled How to do IO in Haskell, which you can find here. Please note that it is not yet finished, but your comments are welcome anyway.
A note about the $ operator.
I suspect that I may be the only person in the world developing book-related software in Haskell. If you are too, please drop an email to info@libra-aries-books.co.uk.
You might also be interested in ISBN.hs, a module for validating and outputting ISBNs, in 10-digit and 13-digit format. It is released under the GPL.
Problems? Comments? Questions? Contact us by email!