And then I tried to tackle Haskell. That was about five years ago, and I think I'm still at beginner/intermediate level with it. But I realized something. These days I have a career and family. Back when I was learning Pascal, I had a lot more time and mental focus on my hands. All the programming languages I've learned since (besides Haskell) were not much different than Pascal, not fundamentally so.
Haskell is fundamentally different. I definitely feel like my past programming experience helped me learn Haskell faster than if I had no experience, but that past experience was also a handicap. I had to discard a lot of assumptions and get to a more basic mindset of what the art of programmming entails. And like a lot of other folks, I found it to be a very rewarding (and useful) experience.