I'd also recommend

Richard Bird. Introduction to Functional Programming in Haskell.

Added to my list, thank you.

While not directly related, taking math courses improves your Haskell skills automatically :) Discrete mathematics is the umbrella term for the math you want, which includes things like graph theory, combinatorics and logic. Intuitionistic logic and type theory are directly related to Haskell.

Looking at the way the classes are structured, apparently most of these classes have a single, identical pre-requisite. Maybe I should bump one of my fall classes back to spring so that I can take the pre-req in the fall, and take a few of those before I graduate. Hm... Try some problems at

http://projecteuler.net/

I've done one or two. I remember getting stuck on a problem involving prime numbers, due to not generating them efficiently enough to have it run in any reasonable amount of time. Maybe I'll dust that off and ask for help here.