Added a wrapper function to produce a GHC with a predefined set of packages.

svn path=/nixpkgs/trunk/; revision=30716

pkgs/development/compilers/ghc/with-packages.nix

@@ -0,0 +1,67 @@
+{stdenv, ghcPlain, packages ? [], makeWrapper}:
+
+stdenv.mkDerivation rec {
+  name = "ghc-${ghcPlain.version}-linkdir";
+
+  allPackages = stdenv.lib.closePropagation packages;
+  buildInputs = allPackages ++ [makeWrapper];
+  propagatedBuildInputs = packages;
+
+  unpackPhase = "true";
+
+  installPhase = ''
+    originalTopDir="${ghcPlain}/lib/ghc-${ghcPlain.version}"
+    originalPkgDir="$originalTopDir/package.conf.d"
+    linkedTopDir="$out/lib"
+    linkedPkgDir="$linkedTopDir/package.conf.d"
+
+    ensureDir $out/bin
+    cd $out/bin
+
+    echo "Generating wrappers ..."
+
+    for prg in ghc ghci ghc-${ghcPlain.version} ghci-${ghcPlain.version}; do
+      makeWrapper ${ghcPlain}/bin/$prg $out/bin/$prg --add-flags "-B$linkedTopDir"
+    done
+
+    for prg in runghc runhaskell; do
+      makeWrapper ${ghcPlain}/bin/$prg $out/bin/$prg --add-flags "-f $out/bin/ghc"
+    done
+
+    for prg in ghc-pkg ghc-pkg-${ghcPlain.version}; do
+      makeWrapper ${ghcPlain}/bin/$prg $out/bin/$prg --add-flags "--global-conf $linkedPkgDir"
+    done
+
+    for prg in hp2ps hpc hasktags hsc2hs haddock haddock-${ghcPlain.version}; do
+      test -x ${ghcPlain}/bin/$prg && ln -s ${ghcPlain}/bin/$prg $out/bin/$prg
+    done
+
+    ensureDir $linkedTopDir
+    cd $linkedTopDir
+
+    if test -f $originalTopDir/settings; then
+      echo "Linking $originalTopDir/settings ..."
+      ln -s $originalTopDir/settings .
+    fi
+
+    ensureDir $linkedPkgDir
+    cd $linkedPkgDir
+
+    echo "Linking $originalPkgDir ..."
+    ln -s $originalPkgDir/*.conf .
+
+    for currentPath in ${stdenv.lib.concatStringsSep " " allPackages}; do
+      currentPkgDir="$currentPath/lib/ghc-pkgs/ghc-${ghcPlain.version}"
+      if test -d $currentPkgDir; then
+        echo "Linking $currentPkgDir ..."
+        ln -s $currentPkgDir/*.conf .
+      fi
+    done
+
+    echo "Generating package cache ..."
+    ${ghcPlain}/bin/ghc-pkg --global-conf $linkedPkgDir recache
+
+  '';
+
+  # inherit ghc.meta;
+}

pkgs/top-level/haskell-packages.nix

@@ -107,6 +107,15 @@ let result = let callPackage = x : y : modifyPrio (newScope result.final x y);
     ghc = ghc;
   };
 
+  # An experimental wrapper around ghcPlain that does not automatically
+  # pick up packages from the profile, but instead has a fixed set of packages
+  # in its global database. The set of packages can be specified as an
+  # argument to this function.
+
+  ghcWithPackages = pkgs : callPackage ../development/compilers/ghc/with-packages.nix {
+    packages = pkgs self;
+  };
+
   # This is the Cabal builder, the function we use to build most Haskell
   # packages. It isn't the Cabal library, which is a core package of GHC
   # and therefore not separately listed here.