Here are some standard reference sites for Haskell.
- Standard library documentation
- A useful Haskell cheatsheet.
- Hackage is a huge repository of Haskell packages. If it isn’t on Hackage, it doesn’t exist. Packages can be automatically downloaded and installed from Hackage using the cabal-install tool.
- Looking for a function but don’t know what it’s called? Want to see the documentation for a particular function? Hoogle searches many standard libraries and can search either by name or by type.
- If you really want the nitty-gritty details of the Haskell language standard, see the 2010 Haskell report.