Major Haskell packages overhaul.

Several changes, some highlights:

  * Structure of haskell-packages.nix updated. It's now easier to
    select different default versions of packages for different
    versions of GHC.

  * GHC 7.0.2 is now default.

  * Haskell Platform 2011.2.0.0 has been added and is now default.

  * Several packages have been updated
    (gtk2hs, gitit, xmonad, darcs, ...).

  * Some old packages have been removed.

svn path=/nixpkgs/trunk/; revision=26288

pkgs/development/libraries/haskell/zlib/0.5.3.1.nix

@@ -0,0 +1,13 @@
+{cabal, zlib}:
+
+cabal.mkDerivation (self : {
+  pname = "zlib";
+  version = "0.5.3.1"; # Haskell Platform 2011.2.0.0
+  sha256 = "1hj56lk4g2zr7acdda39zib1bj02777q0asm5ms9rfj7kp81caiq";
+  # TODO: find out exactly why propagated is needed here (to build other
+  # packages depending on zlib):
+  propagatedBuildInputs = [zlib];
+  meta = {
+    description = "Compression and decompression in the gzip and zlib formats";
+  };
+})