System.Event.Manager [1] contains the following type alias and Show instance:

-- | Callback invoked on I/O events.
type IOCallback = FdKey -> Event -> IO ()



instance Show IOCallback where
    show _ = "IOCallback"

This specialized instance conflicts with the more general instance Show (a -> b) defined in Text.Show.Functions.

Stefan found this conflict when trying to compile the checkers package on ghc 7.0.3. I suspect it will arise with other packages as well.

My suggestion is to remove the specialized Show instance and instead import Text.Show.Functions as needed.

Other thoughts?

[1] http://hackage.haskell.org/packages/archive/base/4.3.1.0/doc/html/src/System-Event-Manager.html

- Conal