Mutable Data structures? Why so hard to find

[atravers]

At what point should I give up on learning Haskell?

For me, Learn you a Haskell was the right introduction to Haskell. Then, I went over to Rosetta Code and tried implementing some of the tasks in Haskell. It took me a few years to feel comfortable with Haskell. It’s been about 12 or 13 years now since I first started learning Haskell. I would say I’m pretty good at Haskell now, but I still use only a subset of it. I’ve tried and failed to understand arrows and lenses, so I just don’t use those features in my code, and I don’t use libraries …

…Rosetta Code: that site appears often in my search results - let’s have a look:

Word frequency - Rosetta Code