Hi, while installing zlib[1] from hackage, I've discovered possible Cabal's misbehaviour. There was no `zlib.h' in my system. runhaskell Setup configure went fine, with no complaints. It was only during build step when missing header had been noticed and an error reported. apt-get install zlib1g-dev; and zlib cabal package installation succeeded, but... Closer to my question. `zlib.h' _is_ mentioned in zlib.cabal: includes: zlib.h According to documentation[2], `includes' "field applies to both header files that are already installed on the system and to those coming with the package to be isntalled." [NB the typo] I think that Cabal should complain of missing headers during configuration step. At least of the ones explicitly mentioned in `includes:' field. 1. http://hackage.haskell.org/cgi-bin/hackage-scripts/package/zlib-0.4.0.4 2. http://www.haskell.org/cabal/release/latest/doc/users-guide/x30.html#buildin... -- vvv