The applicative-numbers package [1] provides an include file.  With ghci, the include file isn't being found, though with cabal+ghc it is found.

My test source is just two lines:

{-# LANGUAGE CPP #-}
#include "ApplicativeNumeric-inc.hs"

I'd sure appreciate it if someone could take a look at the .cabal file [2] and tell me if I'm doing something wrong.  And/or point me to one or more working examples of cabal packages that export include files that are then findable via ghci.

   - Conal

[1] http://hackage.haskell.org/packages/archive/applicative-numbers
[2] http://hackage.haskell.org/packages/archive/applicative-numbers/0.0.2/applicative-numbers.cabal