Type Theory and Functional Programming
ISBN 0-201-41667-0, Addison-Wesley, 1991.
This is now out of print. I had hoped to prepare a revised version before
making it available online,
but sadly this hasn't happened.
So, you can get the original
version, warts and all, from CafePress or
free from here. Any errata will be gratefully received and added to the list