Could you please give me hints where to find materials to learn GHC API?

I know there is  http://www.haskell.org/haskellwiki/GHC/As_a_library, but this contains only 2 examples and I would to learn how to create datatypes, classes, functions etc using GHC API, how to compile them later or generate Haskell code out of them (if its possible).

I would be thnakful for any hint! :)

Thank you,

Wojtek