I would start with Haskell Programming from first principles, as it is recommended by many and it looks good (I have to admit I started with LYAH but content-wise, HPFFP is much better).

I also recommend reading these web documents as a supplement:

http://dev.stephendiehl.com/hask/

https://wiki.haskell.org/All_About_Monads

https://wiki.haskell.org/Typeclassopedia

https://www.fpcomplete.com/blog/2017/09/all-about-strictness

I am now reading Haskell High Performance Programming (https://www.packtpub.com/application-development/haskell-hig...), and while the book is more intermediate (it assumes that you can find the documentation and read the Haskell code yourself), I think it is a good overview of how to use modern Haskell in real projects.

Easily the best one IMO: http://haskellbook.com/ . Unlike LYAH it covers stuff that is actually important to writing real haskell programs like testing code, managing effects via monad transformers, etc.

Also this is one of the best references while you're learning (not good as a tutorial, but chock full of invaluable resources): http://dev.stephendiehl.com/hask/ . TBH I wish every language had an equivalent of this guide.

Haskell Programming From First Principles is costly but extremely good: http://haskellbook.com/

The beginner material in the Haskell WikiBook is pretty solid: https://en.wikibooks.org/wiki/Haskell

found this[1] to be a great introductory course. Might want to have dipped into functional concepts beforehand, though.

Fairly sure it was recommended in here in the past and that's how I came to know it, can't give credit because I sadly don't remember.

[1]https://www.seas.upenn.edu/~cis194/spring13/lectures.html

Another entry in the not Haskell category, Functional Programming in Scala is outstanding.

the spring 2013 edition of cis194[0] seems to be the most commonly recommended from previous threads here. due to its popularity a quick web search leads to a lot of secondary learning resources if you get stuck. i'm currently most of the way through it and it's been well presented and nicely challenging.

[0]http://www.cis.upenn.edu/~cis194/spring13/lectures.html

I learned Haskell from the "Gentle Introduction" (which isn't so gentle), then writing programs, reading documentation, and reading online discussions and threads.

https://www.haskell.org/tutorial/

I'm not OP and it's not haskell, but fsharpforfunandprofit.com really clicked for me, personally.

Real World OCaml is great.

While not purely functional, I also recommend JacaScript Allongé.

Both are free online!