Ask HN: What resources do you recommend for learning Haskell?

Perhaps contrary to most people in this thread, I think you should avoid learning lenses or category theory too early. These are great tools, but they take months or even years to master and are not required to write useful code in the language.

I find Haskell very useful for my projects, but to achieve this I restrict myself to the basic subset of the language (Haskell 2010, no fancy extensions such as type families or GADTs) and use few libraries aside from the core libraries. New features and libraries always carry a high learning curve in Haskell and less popular libraries can be buggy. Instead, you will often be more productive just writing the required functionality from scratch (and it will teach you more too!).

At Jane Street, I saw my coworkers learn functional programming in just one week. (some still struggled with monads in the second week -- if that is you, I can recommend Phil's paper: https://homepages.inf.ed.ac.uk/wadler/papers/marktoberdorf/b...). If you are learning Haskell in your free time and with no one experienced to help, it will obviously take you longer. If you have questions, feel free to post on the Haskell IRC or Reddit. Just don't worry that you need to read another tutorial before getting started :)

I love Haskell Programming from First Principles. It has details for everything. It has plenty of exercises you help you make friends with all of the "esoterica". Once I worked with the rules (e.g. how to make an instance of Applicative), they were a lot more concrete for me.

In Haskell, when you don't understand some detail it really comes back to get you. I read LYaH and I felt like I understood the big picture, but I didn't understand that it was critical to understand the types of _everything_ in an expression that I wrote. (My own failing.)

In summary: I highly recommend. https://HaskellBook.com

My background when I read it: 10+ years programming, 5+ years functional programming, 2 attempts reading LYaH (1 successfully). I still loved it. It would have saved me a lot of grief to start with the HB instead of LYaH.

never learnt it myself, but if I ever tried again, I'd work my way through this: https://wiki.haskell.org/Typeclassopedia

pure functional. no mutations. (state and i/o handled with inscrutable magic).

basically every code base out there could use more functional effort - simple data structures and simple functions that operate on these to return a brand new structure.

Time. Learn a little Haskell this month. Learn a little Haskell in December. Some more over the next few years. In between you will be learning more about programming in general and many other things including how you learn.

There’s no midterm in eight weeks; no final grade after that, and nobody who matters cares how good or bad you are at Haskell. Like most things, it’s not worth having an opinion about.

Give yourself permission to write Haskell poorly because that makes it more likely you will write Haskell. Give yourself permission to not learn Haskell because maybe you like the idea of writing Haskell more than the work of learning Haskell…

…yep, time and permission are the best resources for learning Haskell (or anything else as an adult). It really doesn’t matter what book you pick. Either you enjoy committing or you don’t. Either the work feels satisfying while doing the work or doesn’t.

When the work is truly satisfying, it doesn’t need to be optimized against imagined external opinions. You just do it because it is what you do.

Or not. Good luck.