Hi again.
thank you for the tip! It helps but it's not quite there yet. If you see the program in attachment, I can make it compile only by commenting the type declaration for the second function, otherwise it's the exact same error message as before.
You're probably using the wrong HashMap. There are several packages on Hackage implementing similarly-named data structures (which is confusing, I know, but such is life in a decentralized and open world). You should use what aeson is using (because that's the library defining the Object type synonym). Looking at the import list of http://hackage.haskell.org/packages/archive/aeson/0.6.0.2/doc/html/src/Data-... we see import Data.HashMap.Strict (HashMap) and by checking the package dependencies of aeson, we figure out that this module is provided by the unordered-containers package. Cheers, Andres -- Andres Löh, Haskell Consultant Well-Typed LLP, http://www.well-typed.com