Please use either `cabal install` or `runhaskell Setup configure --user`
to install or configure the package. This is because `runhaskell Setup`
defaults to use global package database, and thus may give spurious error
messages, when the dependencies are installed in user's package database.

For a fresh GHC install on Ubuntu, you may first need to `apt-get install
zlib1g-dev` to get zlib header files.

Troubleshooting:
1. `runhaskell Setup configure` tells that dependencies are missing,
even though I have them installed!

Use `runhaskell Setup configure --user` or see Cabal FAQ:
http://www.haskell.org/cabal/FAQ.html#runghc-setup-complains-of-missing-packages

2. double-conversion dependency breaks the linking process with error:

This is known GHC bug that may appear in FreeBSD and Windows:
http://ghc.haskell.org/trac/ghc/ticket/5289

Workaround is to switch off the flag that makes printing faster:
Append `-f-have-double-conversion` to `cabal install` or `runhaskell Setup
configure` arguments.

3. [Windows] Cannot get `unix` dependency.

Please switch off using bytestring-mmap package by appending flag
`-f-have-mmap` to `cabal install` or `runhaskell Setup configure` arguments.

TODO: try to change *.cabal file so it is done automatically.

4.