Text.ParserCombinators.Parsec requires -package text.

[Claus Reinke]

>> so you could add info about required packages in the object file,
>
>Yes, both of these are good ideas.  However, they both require noodling
>in object files of course, which is non-portable.  Or perhaps creative
>use of 'nm' or 'objdump' would do.
>
>In any case, I think we already arrived at a reasonable solution...

in case you need to revise your solution later: I was thinking of an
equivalent to the rcs ident command, ie a recognisable string pattern
in the object file, automatically created by ghc (here simulated by 
hand) - no non-portable trickery needed:

    --
    module M where
    m_info = "$GHC compiled module: M; needs packages: base, wxhaskell$"
    --

    $ ghc -c M.hs

    $ strings M.o | fgrep \$GHC
    $GHC compiled module: M; needs packages: base, wxhaskell$

cheers,
claus