I am trying to run the haskell code in Ubuntu 9.10 with ghc6, but: Failed to load interface for `Control.Applicative.Error': locations searched:

I am trying to run the haskell code in Ubuntu 9.10 with ghc6, but: Failed to load interface for `Control.Applicative.Error': locations searched: Control/Applicative/Error.hi Control/Applicative/Error.hi-boot Which library am I missing? apt-file search for Control/Applicative/Error.hi yielded none. Help appreciated from all HN-reading haskell'ers.