There is a great Stackoverflow answer about this very thing: http://stackoverflow.com/questions/6398996/good-haskell-source-to-read-and-learn-from http://stack

There is a great Stackoverflow answer about this very thing: http://stackoverflow.com/questions/6398996/good-haskell-source-to-read-and-learn-from http://stackoverflow.com/questions/6398996/good-haskell-sour... Personally, I learned a lot from reading a lot of the Functional Pearls that are published in the Journal of Functional Programming. The XMonad source and the source for Monad-Par are also great to read.