I tend to install haskell packages from apt whenever possible.  One such package is "unix", which appears to come provided by the ghc6 debian package.  I'm trying to cabal install lambdabot and getting the following:

$ cabal install lambdabot

Resolving dependencies...

Configuring lambdabot-4.2.2.1...

Preprocessing executables for lambdabot-4.2.2.1...

Building lambdabot-4.2.2.1...

Main.hs:11:7:

    Could not find module `System.Posix.Signals':

      It is a member of the hidden package `unix-2.4.0.0'.

      Perhaps you need to add `unix' 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:

lambdabot-4.2.2.1 failed during the building phase. The exception was:

ExitFailure 1

I have a feeling this has something to do with the interaction between cabal and apt...

Does anyone have any advice for fixing this issue other than just adding "unix" to the lambdabot.cabal file?

--
         Alex R