diff --git a/pkgs/top-level/haskell-defaults.nix b/pkgs/top-level/haskell-defaults.nix
index 01352707dffc..8f0f0f7d245e 100644
--- a/pkgs/top-level/haskell-defaults.nix
+++ b/pkgs/top-level/haskell-defaults.nix
@@ -16,204 +16,204 @@
   # for a particular GHC version.
 
   ghcHEADPrefs =
-    self : self.haskellPlatformArgs_future self // {
+    super : super.haskellPlatformArgs_future super // {
       haskellPlatform = null;
-      extensibleExceptions = self.extensibleExceptions_0_1_1_4;
+      extensibleExceptions = super.extensibleExceptions_0_1_1_4;
       binary_0_7_1_0 = null;
     };
 
   ghc763Prefs =
-    self : self.haskellPlatformArgs_2013_2_0_0 self // {
-      haskellPlatform = self.haskellPlatform_2013_2_0_0;
-      extensibleExceptions = self.extensibleExceptions_0_1_1_4;
+    super : super.haskellPlatformArgs_2013_2_0_0 super // {
+      haskellPlatform = super.haskellPlatform_2013_2_0_0;
+      extensibleExceptions = super.extensibleExceptions_0_1_1_4;
     };
 
   ghc742Prefs =
-    self : self.haskellPlatformArgs_2012_4_0_0 self // {
-      haskellPlatform = self.haskellPlatform_2012_4_0_0;
-      cabalInstall_1_16_0_2 = self.cabalInstall_1_16_0_2.override { Cabal = self.Cabal_1_16_0_3; };
-      cabal2nix = self.cabal2nix.override { Cabal = self.Cabal_1_16_0_3; hackageDb = self.hackageDb.override { Cabal = self.Cabal_1_16_0_3; }; };
-      haskeline = self.haskeline_0_7_1_1;
-      terminfo = self.terminfo_0_3_2_6;
+    super : super.haskellPlatformArgs_2012_4_0_0 super // {
+      haskellPlatform = super.haskellPlatform_2012_4_0_0;
+      cabalInstall_1_16_0_2 = super.cabalInstall_1_16_0_2.override { Cabal = super.Cabal_1_16_0_3; };
+      cabal2nix = super.cabal2nix.override { Cabal = super.Cabal_1_16_0_3; hackageDb = super.hackageDb.override { Cabal = super.Cabal_1_16_0_3; }; };
+      haskeline = super.haskeline_0_7_1_1;
+      terminfo = super.terminfo_0_3_2_6;
     };
 
   ghc741Prefs =
-    self : self.haskellPlatformArgs_2012_2_0_0 self // {
-      haskellPlatform = self.haskellPlatform_2012_2_0_0;
-      cabalInstall_1_16_0_2 = self.cabalInstall_1_16_0_2.override { Cabal = self.Cabal_1_16_0_3; };
-      cabal2nix = self.cabal2nix.override { Cabal = self.Cabal_1_16_0_3; hackageDb = self.hackageDb.override { Cabal = self.Cabal_1_16_0_3; }; };
-      haskeline = self.haskeline_0_7_1_1;
-      terminfo = self.terminfo_0_3_2_6;
+    super : super.haskellPlatformArgs_2012_2_0_0 super // {
+      haskellPlatform = super.haskellPlatform_2012_2_0_0;
+      cabalInstall_1_16_0_2 = super.cabalInstall_1_16_0_2.override { Cabal = super.Cabal_1_16_0_3; };
+      cabal2nix = super.cabal2nix.override { Cabal = super.Cabal_1_16_0_3; hackageDb = super.hackageDb.override { Cabal = super.Cabal_1_16_0_3; }; };
+      haskeline = super.haskeline_0_7_1_1;
+      terminfo = super.terminfo_0_3_2_6;
     };
 
   ghc722Prefs =
-    self : self.haskellPlatformArgs_2012_2_0_0 self // {
-      haskellPlatform = self.haskellPlatform_2012_2_0_0;
-      deepseq = self.deepseq_1_3_0_2;
-      cabalInstall_0_14_0 = self.cabalInstall_0_14_0.override { Cabal = self.Cabal_1_14_0; };
-      cabalInstall_1_16_0_2 = self.cabalInstall_1_16_0_2.override { Cabal = self.Cabal_1_16_0_3; };
-      cabalInstall_1_20_0_1 = self.cabalInstall_1_20_0_1.override { HTTP = self.HTTP_4000_2_14; };
-      cabalInstall = self.cabalInstall_0_14_0.override { Cabal = self.Cabal_1_14_0; };
-      cabal2nix = self.cabal2nix.override { Cabal = self.Cabal_1_16_0_3; hackageDb = self.hackageDb.override { Cabal = self.Cabal_1_16_0_3; }; };
-      binary = self.binary_0_6_0_0;
-      prettyShow = self.prettyShow_1_2;
-      quickcheckIo = self.quickcheckIo.override {
-        HUnit = self.HUnit_1_2_5_2;
-        QuickCheck = self.QuickCheck2;
+    super : super.haskellPlatformArgs_2012_2_0_0 super // {
+      haskellPlatform = super.haskellPlatform_2012_2_0_0;
+      deepseq = super.deepseq_1_3_0_2;
+      cabalInstall_0_14_0 = super.cabalInstall_0_14_0.override { Cabal = super.Cabal_1_14_0; };
+      cabalInstall_1_16_0_2 = super.cabalInstall_1_16_0_2.override { Cabal = super.Cabal_1_16_0_3; };
+      cabalInstall_1_20_0_1 = super.cabalInstall_1_20_0_1.override { HTTP = super.HTTP_4000_2_14; };
+      cabalInstall = super.cabalInstall_0_14_0.override { Cabal = super.Cabal_1_14_0; };
+      cabal2nix = super.cabal2nix.override { Cabal = super.Cabal_1_16_0_3; hackageDb = super.hackageDb.override { Cabal = super.Cabal_1_16_0_3; }; };
+      binary = super.binary_0_6_0_0;
+      prettyShow = super.prettyShow_1_2;
+      quickcheckIo = super.quickcheckIo.override {
+        HUnit = super.HUnit_1_2_5_2;
+        QuickCheck = super.QuickCheck2;
       };
-      hspecExpectations = self.hspecExpectations.override {
-        HUnit = self.HUnit_1_2_5_2;
+      hspecExpectations = super.hspecExpectations.override {
+        HUnit = super.HUnit_1_2_5_2;
       };
-      haskeline = self.haskeline_0_7_1_1;
-      terminfo = self.terminfo_0_3_2_6;
+      haskeline = super.haskeline_0_7_1_1;
+      terminfo = super.terminfo_0_3_2_6;
     };
 
   ghc721Prefs = ghc722Prefs;
 
   ghc704Prefs =
-    self : self.haskellPlatformArgs_2011_4_0_0 self // {
-      haskellPlatform = self.haskellPlatform_2011_4_0_0;
-      cabalInstall_0_14_0 = self.cabalInstall_0_14_0.override { Cabal = self.Cabal_1_14_0; };
-      cabalInstall_1_16_0_2 = self.cabalInstall_1_16_0_2.override { Cabal = self.Cabal_1_16_0_3; };
-      monadPar = self.monadPar_0_1_0_3;
-      jailbreakCabal = self.jailbreakCabal.override { Cabal = self.disableTest self.Cabal_1_14_0; };
-      cabal2nix = self.cabal2nix.override { Cabal = self.Cabal_1_16_0_3; hackageDb = self.hackageDb.override { Cabal = self.Cabal_1_16_0_3; }; };
-      prettyShow = self.prettyShow_1_2;
-      binary = self.binary_0_6_0_0;
-      Cabal_1_18_1_3 = self.Cabal_1_18_1_3.override { deepseq = self.deepseq_1_3_0_2; };
-      quickcheckIo = self.quickcheckIo.override {
-        HUnit = self.HUnit_1_2_5_2;
-        QuickCheck = self.QuickCheck2;
+    super : super.haskellPlatformArgs_2011_4_0_0 super // {
+      haskellPlatform = super.haskellPlatform_2011_4_0_0;
+      cabalInstall_0_14_0 = super.cabalInstall_0_14_0.override { Cabal = super.Cabal_1_14_0; };
+      cabalInstall_1_16_0_2 = super.cabalInstall_1_16_0_2.override { Cabal = super.Cabal_1_16_0_3; };
+      monadPar = super.monadPar_0_1_0_3;
+      jailbreakCabal = super.jailbreakCabal.override { Cabal = super.disableTest super.Cabal_1_14_0; };
+      cabal2nix = super.cabal2nix.override { Cabal = super.Cabal_1_16_0_3; hackageDb = super.hackageDb.override { Cabal = super.Cabal_1_16_0_3; }; };
+      prettyShow = super.prettyShow_1_2;
+      binary = super.binary_0_6_0_0;
+      Cabal_1_18_1_3 = super.Cabal_1_18_1_3.override { deepseq = super.deepseq_1_3_0_2; };
+      quickcheckIo = super.quickcheckIo.override {
+        HUnit = super.HUnit_1_2_5_2;
+        QuickCheck = super.QuickCheck2;
       };
-      hspecExpectations = self.hspecExpectations.override {
-        HUnit = self.HUnit_1_2_5_2;
+      hspecExpectations = super.hspecExpectations.override {
+        HUnit = super.HUnit_1_2_5_2;
       };
-      haskeline = self.haskeline_0_7_1_1;
-      terminfo = self.terminfo_0_3_2_6;
+      haskeline = super.haskeline_0_7_1_1;
+      terminfo = super.terminfo_0_3_2_6;
     };
 
   ghc703Prefs =
-    self : self.haskellPlatformArgs_2011_2_0_1 self // {
-      haskellPlatform = self.haskellPlatform_2011_2_0_1;
-      cabalInstall_0_14_0 = self.cabalInstall_0_14_0.override { Cabal = self.Cabal_1_14_0; zlib = self.zlib_0_5_3_3; };
-      cabalInstall_1_16_0_2 = self.cabalInstall_1_16_0_2.override { Cabal = self.Cabal_1_16_0_3; zlib = self.zlib_0_5_3_3; };
-      monadPar = self.monadPar_0_1_0_3;
-      jailbreakCabal = self.jailbreakCabal.override { Cabal = self.disableTest self.Cabal_1_14_0; };
-      cabal2nix = self.cabal2nix.override { Cabal = self.Cabal_1_16_0_3; hackageDb = self.hackageDb.override { Cabal = self.Cabal_1_16_0_3; }; };
-      prettyShow = self.prettyShow_1_2;
-      binary = self.binary_0_6_0_0;
-      Cabal_1_18_1_3 = self.Cabal_1_18_1_3.override { deepseq = self.deepseq_1_3_0_2; };
-      quickcheckIo = self.quickcheckIo.override {
-        HUnit = self.HUnit_1_2_5_2;
-        QuickCheck = self.QuickCheck2;
+    super : super.haskellPlatformArgs_2011_2_0_1 super // {
+      haskellPlatform = super.haskellPlatform_2011_2_0_1;
+      cabalInstall_0_14_0 = super.cabalInstall_0_14_0.override { Cabal = super.Cabal_1_14_0; zlib = super.zlib_0_5_3_3; };
+      cabalInstall_1_16_0_2 = super.cabalInstall_1_16_0_2.override { Cabal = super.Cabal_1_16_0_3; zlib = super.zlib_0_5_3_3; };
+      monadPar = super.monadPar_0_1_0_3;
+      jailbreakCabal = super.jailbreakCabal.override { Cabal = super.disableTest super.Cabal_1_14_0; };
+      cabal2nix = super.cabal2nix.override { Cabal = super.Cabal_1_16_0_3; hackageDb = super.hackageDb.override { Cabal = super.Cabal_1_16_0_3; }; };
+      prettyShow = super.prettyShow_1_2;
+      binary = super.binary_0_6_0_0;
+      Cabal_1_18_1_3 = super.Cabal_1_18_1_3.override { deepseq = super.deepseq_1_3_0_2; };
+      quickcheckIo = super.quickcheckIo.override {
+        HUnit = super.HUnit_1_2_5_2;
+        QuickCheck = super.QuickCheck2;
       };
-      hspecExpectations = self.hspecExpectations.override {
-        HUnit = self.HUnit_1_2_5_2;
+      hspecExpectations = super.hspecExpectations.override {
+        HUnit = super.HUnit_1_2_5_2;
       };
-      haskeline = self.haskeline_0_7_1_1;
-      terminfo = self.terminfo_0_3_2_6;
+      haskeline = super.haskeline_0_7_1_1;
+      terminfo = super.terminfo_0_3_2_6;
     };
 
   ghc702Prefs = ghc701Prefs;
 
   ghc701Prefs =
-    self : self.haskellPlatformArgs_2011_2_0_0 self // {
-      haskellPlatform = self.haskellPlatform_2011_2_0_0;
-      cabalInstall_0_14_0 = self.cabalInstall_0_14_0.override { Cabal = self.Cabal_1_14_0; zlib = self.zlib_0_5_3_3; };
-      cabalInstall_1_16_0_2 = self.cabalInstall_1_16_0_2.override { Cabal = self.Cabal_1_16_0_3; zlib = self.zlib_0_5_3_3; };
-      monadPar = self.monadPar_0_1_0_3;
-      jailbreakCabal = self.jailbreakCabal.override { Cabal = self.disableTest self.Cabal_1_14_0; };
-      cabal2nix = self.cabal2nix.override { Cabal = self.Cabal_1_16_0_3; hackageDb = self.hackageDb.override { Cabal = self.Cabal_1_16_0_3; }; };
-      prettyShow = self.prettyShow_1_2;
-      binary = self.binary_0_6_0_0;
-      Cabal_1_18_1_3 = self.Cabal_1_18_1_3.override { deepseq = self.deepseq_1_3_0_2; };
-      quickcheckIo = self.quickcheckIo.override {
-        HUnit = self.HUnit_1_2_5_2;
-        QuickCheck = self.QuickCheck2;
+    super : super.haskellPlatformArgs_2011_2_0_0 super // {
+      haskellPlatform = super.haskellPlatform_2011_2_0_0;
+      cabalInstall_0_14_0 = super.cabalInstall_0_14_0.override { Cabal = super.Cabal_1_14_0; zlib = super.zlib_0_5_3_3; };
+      cabalInstall_1_16_0_2 = super.cabalInstall_1_16_0_2.override { Cabal = super.Cabal_1_16_0_3; zlib = super.zlib_0_5_3_3; };
+      monadPar = super.monadPar_0_1_0_3;
+      jailbreakCabal = super.jailbreakCabal.override { Cabal = super.disableTest super.Cabal_1_14_0; };
+      cabal2nix = super.cabal2nix.override { Cabal = super.Cabal_1_16_0_3; hackageDb = super.hackageDb.override { Cabal = super.Cabal_1_16_0_3; }; };
+      prettyShow = super.prettyShow_1_2;
+      binary = super.binary_0_6_0_0;
+      Cabal_1_18_1_3 = super.Cabal_1_18_1_3.override { deepseq = super.deepseq_1_3_0_2; };
+      quickcheckIo = super.quickcheckIo.override {
+        HUnit = super.HUnit_1_2_5_2;
+        QuickCheck = super.QuickCheck2;
       };
-      hspecExpectations = self.hspecExpectations.override {
-        HUnit = self.HUnit_1_2_5_2;
+      hspecExpectations = super.hspecExpectations.override {
+        HUnit = super.HUnit_1_2_5_2;
       };
-      haskeline = self.haskeline_0_7_1_1;
-      terminfo = self.terminfo_0_3_2_6;
+      haskeline = super.haskeline_0_7_1_1;
+      terminfo = super.terminfo_0_3_2_6;
     };
 
   ghc6123Prefs = ghc6122Prefs;
 
   ghc6122Prefs =
-    self : self.haskellPlatformArgs_2010_2_0_0 self // {
-      haskellPlatform = self.haskellPlatform_2010_2_0_0;
-      mtl1 = self.mtl_1_1_0_2;
-      monadPar = self.monadPar_0_1_0_3;
-      deepseq = self.deepseq_1_1_0_2;
+    super : super.haskellPlatformArgs_2010_2_0_0 super // {
+      haskellPlatform = super.haskellPlatform_2010_2_0_0;
+      mtl1 = super.mtl_1_1_0_2;
+      monadPar = super.monadPar_0_1_0_3;
+      deepseq = super.deepseq_1_1_0_2;
       # deviating from Haskell platform here, to make some packages (notably statistics) compile
-      jailbreakCabal = self.jailbreakCabal.override { Cabal = self.disableTest self.Cabal_1_14_0; };
-      cabal2nix = self.cabal2nix.override { Cabal = self.Cabal_1_16_0_3; hackageDb = self.hackageDb.override { Cabal = self.Cabal_1_16_0_3; }; };
-      binary = self.binary_0_6_0_0;
-      cabalInstall_1_16_0_2 = self.cabalInstall_1_16_0_2.override {
-        Cabal = self.Cabal_1_16_0_3; zlib = self.zlib_0_5_3_3;
-        mtl = self.mtl_2_1_2;
-        HTTP = self.HTTP_4000_1_1.override { mtl = self.mtl_2_1_2; };
+      jailbreakCabal = super.jailbreakCabal.override { Cabal = super.disableTest super.Cabal_1_14_0; };
+      cabal2nix = super.cabal2nix.override { Cabal = super.Cabal_1_16_0_3; hackageDb = super.hackageDb.override { Cabal = super.Cabal_1_16_0_3; }; };
+      binary = super.binary_0_6_0_0;
+      cabalInstall_1_16_0_2 = super.cabalInstall_1_16_0_2.override {
+        Cabal = super.Cabal_1_16_0_3; zlib = super.zlib_0_5_3_3;
+        mtl = super.mtl_2_1_2;
+        HTTP = super.HTTP_4000_1_1.override { mtl = super.mtl_2_1_2; };
       };
-      quickcheckIo = self.quickcheckIo.override {
-        HUnit = self.HUnit_1_2_5_2;
-        QuickCheck = self.QuickCheck2;
+      quickcheckIo = super.quickcheckIo.override {
+        HUnit = super.HUnit_1_2_5_2;
+        QuickCheck = super.QuickCheck2;
       };
-      hspecExpectations = self.hspecExpectations.override {
-        HUnit = self.HUnit_1_2_5_2;
+      hspecExpectations = super.hspecExpectations.override {
+        HUnit = super.HUnit_1_2_5_2;
       };
-      haskeline = self.haskeline_0_7_1_1;
-      terminfo = self.terminfo_0_3_2_6;
+      haskeline = super.haskeline_0_7_1_1;
+      terminfo = super.terminfo_0_3_2_6;
     };
 
   ghc6121Prefs =
-    self : self.haskellPlatformArgs_2010_1_0_0 self // {
-      haskellPlatform = self.haskellPlatform_2010_1_0_0;
-      mtl1 = self.mtl_1_1_0_2;
-      extensibleExceptions = self.extensibleExceptions_0_1_1_0;
-      deepseq = self.deepseq_1_1_0_2;
-      monadPar = self.monadPar_0_1_0_3;
+    super : super.haskellPlatformArgs_2010_1_0_0 super // {
+      haskellPlatform = super.haskellPlatform_2010_1_0_0;
+      mtl1 = super.mtl_1_1_0_2;
+      extensibleExceptions = super.extensibleExceptions_0_1_1_0;
+      deepseq = super.deepseq_1_1_0_2;
+      monadPar = super.monadPar_0_1_0_3;
       # deviating from Haskell platform here, to make some packages (notably statistics) compile
-      jailbreakCabal = self.jailbreakCabal.override { Cabal = self.disableTest self.Cabal_1_14_0; };
-      cabal2nix = self.cabal2nix.override { Cabal = self.Cabal_1_16_0_3; hackageDb = self.hackageDb.override { Cabal = self.Cabal_1_16_0_3; }; };
-      binary = self.binary_0_6_0_0;
-      cabalInstall_1_16_0_2 = self.cabalInstall_1_16_0_2.override {
-        Cabal = self.Cabal_1_16_0_3;
-        zlib = self.zlib_0_5_3_3;
-        mtl = self.mtl_2_1_2;
-        HTTP = self.HTTP_4000_1_1.override { mtl = self.mtl_2_1_2; };
+      jailbreakCabal = super.jailbreakCabal.override { Cabal = super.disableTest super.Cabal_1_14_0; };
+      cabal2nix = super.cabal2nix.override { Cabal = super.Cabal_1_16_0_3; hackageDb = super.hackageDb.override { Cabal = super.Cabal_1_16_0_3; }; };
+      binary = super.binary_0_6_0_0;
+      cabalInstall_1_16_0_2 = super.cabalInstall_1_16_0_2.override {
+        Cabal = super.Cabal_1_16_0_3;
+        zlib = super.zlib_0_5_3_3;
+        mtl = super.mtl_2_1_2;
+        HTTP = super.HTTP_4000_1_1.override { mtl = super.mtl_2_1_2; };
       };
-      quickcheckIo = self.quickcheckIo.override {
-        HUnit = self.HUnit_1_2_5_2;
-        QuickCheck = self.QuickCheck2;
+      quickcheckIo = super.quickcheckIo.override {
+        HUnit = super.HUnit_1_2_5_2;
+        QuickCheck = super.QuickCheck2;
       };
-      hspecExpectations = self.hspecExpectations.override {
-        HUnit = self.HUnit_1_2_5_2;
+      hspecExpectations = super.hspecExpectations.override {
+        HUnit = super.HUnit_1_2_5_2;
       };
-      haskeline = self.haskeline_0_7_1_1;
-      terminfo = self.terminfo_0_3_2_6;
+      haskeline = super.haskeline_0_7_1_1;
+      terminfo = super.terminfo_0_3_2_6;
     };
 
   ghc6104Prefs =
-    self : self.haskellPlatformArgs_2009_2_0_2 self // {
-      haskellPlatform = self.haskellPlatform_2009_2_0_2;
-      mtl = self.mtl_1_1_0_2;
-      mtl1 = self.mtl_1_1_0_2;
-      extensibleExceptions = self.extensibleExceptions_0_1_1_0;
-      text = self.text_0_11_0_6;
-      deepseq = self.deepseq_1_1_0_2;
-      monadPar = self.monadPar_0_1_0_3;
+    super : super.haskellPlatformArgs_2009_2_0_2 super // {
+      haskellPlatform = super.haskellPlatform_2009_2_0_2;
+      mtl = super.mtl_1_1_0_2;
+      mtl1 = super.mtl_1_1_0_2;
+      extensibleExceptions = super.extensibleExceptions_0_1_1_0;
+      text = super.text_0_11_0_6;
+      deepseq = super.deepseq_1_1_0_2;
+      monadPar = super.monadPar_0_1_0_3;
       # deviating from Haskell platform here, to make some packages (notably statistics) compile
-      jailbreakCabal = self.jailbreakCabal.override { Cabal = self.disableTest self.Cabal_1_14_0; };
-      binary = self.binary_0_6_0_0;
-      cabalInstall_1_16_0_2 = self.cabalInstall_1_16_0_2.override {
-        Cabal = self.Cabal_1_16_0_3;
-        zlib = self.zlib_0_5_3_3;
-        mtl = self.mtl_2_1_2;
-        HTTP = self.HTTP_4000_1_1.override { mtl = self.mtl_2_1_2; };
+      jailbreakCabal = super.jailbreakCabal.override { Cabal = super.disableTest super.Cabal_1_14_0; };
+      binary = super.binary_0_6_0_0;
+      cabalInstall_1_16_0_2 = super.cabalInstall_1_16_0_2.override {
+        Cabal = super.Cabal_1_16_0_3;
+        zlib = super.zlib_0_5_3_3;
+        mtl = super.mtl_2_1_2;
+        HTTP = super.HTTP_4000_1_1.override { mtl = super.mtl_2_1_2; };
       };
-      haskeline = self.haskeline_0_7_1_1;
-      terminfo = self.terminfo_0_3_2_6;
+      haskeline = super.haskeline_0_7_1_1;
+      terminfo = super.terminfo_0_3_2_6;
     };
 
   # Abstraction for Haskell packages collections
@@ -221,20 +221,22 @@
    ({ ghcPath
     , ghcBinary ? ghc6101Binary
     , prefFun
-    , extraPrefs ? (x : {})
+    , extension ? (self : super : {})
     , profExplicit ? false, profDefault ? false
     , modifyPrio ? lowPrio
     , extraArgs ? {}
     } :
-      import ./haskell-packages.nix {
-        inherit pkgs newScope modifyPrio;
-        prefFun = self : super : self // prefFun super // extraPrefs super;
-        # prefFun = self : super : self;
-        enableLibraryProfiling =
-          if profExplicit then profDefault
-                          else config.cabal.libraryProfiling or profDefault;
-        ghc = callPackage ghcPath ({ ghc = ghcBinary; } // extraArgs);
-      });
+    let haskellPackagesClass = import ./haskell-packages.nix {
+          inherit pkgs newScope modifyPrio;
+          enableLibraryProfiling =
+            if profExplicit then profDefault
+                            else config.cabal.libraryProfiling or profDefault;
+          ghc = callPackage ghcPath ({ ghc = ghcBinary; } // extraArgs);
+        };
+        haskellPackagesPrefsClass = self : let super = haskellPackagesClass self; in super // prefFun super;
+        haskellPackagesExtensionClass = self : let super = haskellPackagesPrefsClass self; in super // extension self super;
+        haskellPackages = haskellPackagesExtensionClass haskellPackages;
+    in haskellPackages);
 
   defaultVersionPrioFun =
     profDefault :
diff --git a/pkgs/top-level/haskell-packages.nix b/pkgs/top-level/haskell-packages.nix
index 1e7a72977582..edb21dd4303c 100644
--- a/pkgs/top-level/haskell-packages.nix
+++ b/pkgs/top-level/haskell-packages.nix
@@ -58,7 +58,7 @@
 #
 # For most packages, however, we keep only one version, and use default.nix.
 
-{ pkgs, newScope, ghc, prefFun, modifyPrio ? (x : x)
+{ pkgs, newScope, ghc, modifyPrio ? (x : x)
 , enableLibraryProfiling ? false
 , enableSharedLibraries ? pkgs.stdenv.lib.versionOlder "7.7" ghc.version
 , enableSharedExecutables ? pkgs.stdenv.lib.versionOlder "7.7" ghc.version
@@ -70,17 +70,13 @@
 # modifyPrio argument can be set to lowPrio to make all Haskell packages have
 # low priority.
 
-let result = let callPackage = x : y : modifyPrio (newScope result.finalReturn x y);
-                 self = (prefFun result) result; in
+self : let callPackage = x : y : modifyPrio (newScope self x y); in
 
 # Indentation deliberately broken at this point to keep the bulk
 # of this file at a low indentation level.
 
 {
-
-  finalReturn = self;
-
-  callPackage = callPackage;
+  inherit callPackage;
 
   # GHC and its wrapper
   #
@@ -3171,6 +3167,4 @@ let result = let callPackage = x : y : modifyPrio (newScope result.finalReturn x
 
 # End of the main part of the file.
 
-};
-
-in result.finalReturn
+}