I truly recommend Graham HUTTON, Programming in Haskell - http://www.cs.nott.ac.uk/~gmh/book.html

The most important detail for a beginner is that the examples from this book just run!

Good luck!

I truly recommend Graham HUTTON, Programming in Haskell - http://www.cs.nott.ac.uk/~gmh/book.html

The most important detail for a beginner is that the examples from this book just run!

Good luck!

I found the book from Simon Thompson: Haskell: The Craft of Functional Programming most useful.

For several years, I've assigned my students in "Principles of Programming Languages" readings from "Learn You a Haskell for Great Good". It's free, it's fun, and it gets the important points across with concrete examples. I'm not sure what I would use if I were spending more than a few weeks on Haskell, though.

There is also "Real World Haskell" by Bryan O'Sullivan, John Goerzen, and Don Stewart. That book is published by O'Reilly, and like many O'Reilly books, it is  available for free online: http://book.realworldhaskell.org/. 

The online version is particularly useful, as it also contains comments by users, which has ensured that even the tiniest errors are caught and explanations are bootstrapped and perfected.

For a bit more special purpose, the book "Parallel and Concurrent Programming in Haskell" by Simon Marlow (2013) is essential. This O'Reilly book is available for free online: 

http://chimera.labs.oreilly.com/books/1230000000929/index.html

To start learning Haskell I highly recommend "Learn You a Haskell for great good", see Stephen Bloch's answer. Alternatively there is an early release of "Haskell programming from first principles" ($59).

Then you could continue with the web pages "Typeclassopedia" and "What I Wish I Knew When Learning Haskell" (by Stephen Diehl), which deal with more advanced concepts such as: programming with Arrows, polymorphism of kinds. I recommend to read the migration notes from GHC, the Haskell compiler, as there are important ongoing changes not reflected in "Learn You a Haskell for great good".

As documentation is a living material, the Wikibook on Haskell has also a lot of interesting articles.

A longer list of resources can be found on the documentation page on the Haskell website. "Parallel and Concurrent Programming in Haskell" is a very good book (see Robin T. Bye's answer). 

And finally, you will found an overview of the prolific Haskell's community on the Haskell's News page: it gathers a mailing list, Reddit, Stack Overflow, Twitter, etc. and a selection of blog's posts.

http://learnyouahaskell.com/

https://www.haskell.org/documentation

https://en.wikibooks.org/wiki/Haskell

http://haskellbook.com/

https://wiki.haskell.org/Typeclassopedia

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

https://ghc.haskell.org/trac/ghc/wiki/Migration/7.10

https://www.haskell.org/news