Dropped obsolete Haskell packages.

- convertible-text: deprecated by author
 - failure: obsolete version 0.1.2
 - attempt: obsolete version 0.3.1.1

svn path=/nixpkgs/trunk/; revision=33470

pkgs/development/libraries/haskell/failure/0.1.2.nix

@@ -1,14 +0,0 @@
-{ cabal }:
-
-cabal.mkDerivation (self: {
-  pname = "failure";
-  version = "0.1.2";
-  sha256 = "14pwj0zb5kk2wadpddanxv3kr0hzklxhzbprmkh40yn1dbwgdas4";
-  meta = {
-    homepage = "http://www.haskell.org/haskellwiki/Failure";
-    description = "A simple type class for success/failure computations";
-    license = self.stdenv.lib.licenses.bsd3;
-    platforms = self.ghc.meta.platforms;
-    maintainers = [ self.stdenv.lib.maintainers.andres ];
-  };
-})