I've had a try with Haskell, at the begining of my studies with little success. Now I'm getting back to it.
I've started with some reading. Mostly Gentle Introduction to Haskell 98 and Learn you a Haskell , these two I find complementing themselves - the first one being more theoretical, the latter more practical.
Unfortunately that has not given as much as I hoped. I realised that if I was given a certain task to do in Haskell I'd have to begin with a long scratch on my head and a long Internet search.
I realised that what I need is some exercise.
This is what I've found so far to help me with that : 6 problems and 99 problems.
I've done a bit of both and now I feel more like a Haskell Programmer. More like 0.0002 per mill more. ;)
99 problems are really problems for Prolog (a declarative programming language) solved in Haskell. I've had to learn some Prolog 2 semesters back thus I'm not that excited to be doing them.
I will definitely look for more and post some problems of my own (with solutions) soon.