In Debian systems, ./Setup.hs doesn't include links to the GHC docs, giving the
following error message:

Warning: cannot use package base-2.0:
   HTML directory /usr/share/ghc-6.6/html/libraries/base does not exist.
Warning: Algebra.Geometric.Area: the following names could not be resolved:
    Double
Warning: Algebra.Geometric.Contour: the following names could not be resolved:
    Ord Show Eq Double
Warning: Algebra.Geometric.Gpc: the following names could not be resolved:
    IO unsafePerformIO Ptr CInt Storable Int FilePath Bool Maybe Nothing String True False CChar

There's a bug filled against the Debian package in
http://bugs.debian.org/401785 .