* added generic Cabal builder

* transformed zlib, vty, binary, X11 to use generic Cabal builder
* note that Cabal library packages are now by default prefixed with "haskell-"

svn path=/nixpkgs/trunk/; revision=10247

pkgs/development/libraries/haskell/cabal/cabal.nix

@@ -0,0 +1,92 @@
+# generic builder for Cabal packages
+
+attrs :
+{
+  mkDerivation =
+    transform :
+    let dtransform =
+          self : {
+
+            # pname should be defined by the client to be the package basename
+            # version should be defined by the client to be the package version
+ 
+            # fname is the internal full name of the package
+            fname = "${self.pname}-${self.version}";
+
+	    # name is the external full name of the package; usually we prefix
+	    # all packages with haskell- to avoid name clashes for libraries;
+	    # if that is not desired (for applications), name can be set to
+	    # fname.
+            name = "haskell-${self.fname}"; 
+
+            # the default download location for Cabal packages is Hackage,
+            # you still have to specify the checksum
+            src = attrs.fetchurl {
+              url = "http://hackage.haskell.org/packages/archive/${self.pname}/${self.version}/${self.fname}.tar.gz";
+              inherit (self) sha256;
+            };
+
+            # default buildInputs are just ghc, if more buildInputs are required
+            # buildInputs can be extended by the client, but often propagatedBuildInputs
+            # is preferable anyway
+            buildInputs = [attrs.ghc];
+
+            # we make sure that propagatedBuildInputs is defined, so that we don't
+            # have to check for its existence
+            propagatedBuildInputs = [];
+
+            # library directories that have to be added to the Cabal files
+            extraLibDirs = map (x : x + "/lib") self.propagatedBuildInputs;
+
+            # file(s) that have to be patched with information about extra libraries;
+            # can be redefined to the empty list by the client if this is not desired
+            patchLibFiles = [ "${self.pname}.cabal" ];
+
+            # patches files, compiles Setup, and configures
+            configurePhase = ''
+              eval "$preConfigure"
+
+              for i in ${toString self.patchLibFiles}; do
+                echo "patching $i"
+                test -f $i && sed -i '/extra-libraries/ { s|\( *\)extra-libraries.*|&\n\1extra-lib-dirs: ${toString self.extraLibDirs}| }' $i
+              done
+              for i in Setup.hs Setup.lhs; do
+                test -f $i && ghc --make $i
+              done
+              ./Setup configure --prefix="$out"
+
+              eval "$postConfigure"
+            '';
+
+            # builds via Cabal
+            buildPhase = ''
+              eval "$preBuild"
+
+              ./Setup build
+
+              eval "$postBuild"
+            '';
+
+	    # installs via Cabal; creates a registration file for nix-support
+	    # so that the package can be used in other Haskell-builds; also
+	    # creates a register-${name}.sh in userspace that can be used to
+	    # register the library in a user environment (but this scheme
+	    # should sooner or later be deprecated in favour of using a
+	    # ghc-wrapper).
+            installPhase = ''
+              eval "$preInstall"
+
+              ./Setup copy
+              ./Setup register --gen-script
+              mkdir $out/nix-support
+              sed -i 's/|.*\(ghc-pkg update\)/| \1/' register.sh
+              cp register.sh $out/nix-support/register-ghclib.sh
+              sed -i 's/\(ghc-pkg update\)/\1 --user/' register.sh
+              mkdir $out/bin
+              cp register.sh $out/bin/register-${self.name}.sh
+
+              eval "$postInstall"
+            '';
+          };
+    in  attrs.stdenv.mkDerivation ((rec { f = dtransform f // transform f; }).f);
+}