What are some good intermediate problems and projects for learning Haskell? [closed]

I just recently started diving into Real World Haskell and the book provides some good practice exercises.

However, I’d like some suggestions for specific problems people have solved or projects they’ve completed that have really helped them to better understand the language and its capabilities. What sort of things can I throw myself at that are really going to challenge me?

I have a moderate understanding of the language and no previous experience with other functional languages; Haskell is my first jump into this arena.

What are some good intermediate problems and projects for learning Haskell? [closed]