Haskell is hard language I have like tried to learn it several times and no luck. I did not have same problem with Clojure and Rust where I was productive like first day.
Curious what method you used? I recently bought a book, I'm only learning it to port a Haskell project to C++, if I can even do that.
I have read http://learnyouahaskell.com/chapters and then start implementing something useful based on examples. This process read book x and then implement something has worked with all other languages. I think big part is that Haskell has all kinda custom operators which are basically ungooglable.