Hi
All the puffing about the advantages of strong typing look pretty silly if code hangs up on an incomplete pattern.
Okay... people who don't worry so much about incomplete patterns believe that they get things done.
There are trade offs in type systems about how much effort you want to require of the user and how much the type system will catch. Haskell's type system is at a point that does a lot with very little. You can do ridiculously more if you don't mind requiring more from the user.
I know Catch got mentioned at the beginning of this thread, but it does read like an advert for Catch :) You can have existing Haskell with no annotations that is proven free from pattern-match errors automatically. You can do the trick of saying error "this branch cannot be reached", then Catch will validate that you are correct. http://www-users.cs.york.ac.uk/~ndm/catch/ Thanks Neil