Dear cafe, I have just upgraded to GHC 7.4, and now I run into some compilation problems. Specifically, I have a package that needs both Data.Array.Unboxed and System.IO.Unsafe. But I cannot enable both base and haskell98 in a cabal file. is there any way out of this? If I enable both haskell98 and base, I get Query.hs:1:1: Ambiguous module name `Prelude': it was found in multiple packages: base haskell98-2.0.0.1 cabal: Error: some packages failed to install: as documented elsewhere (http://hackage.haskell.org/trac/ghc/ticket/4958) With haskell98 replacing base, I get Query.hs:55:8: Could not find module `System.IO.Unsafe' It is a member of the hidden package `base'. Perhaps you need to add `base' to the build-depends in your .cabal file. Use -v to see a list of the files searched for. cabal: Error: some packages failed to install: and without haskell98 or array, cabal tells me to add those to .cabal build-depends. So how can I use the Data.Array.Unboxed package together with all the stuff from base that is not in haskell98? Thanks, Tom