Update based on comments to pull request

pkgs/applications/science/molecular-dynamics/gromacs/4.5.5.nix

@@ -1,26 +0,0 @@
-
-{ stdenv, fetchurl, cmake,
-  singlePrec ? true,
-  fftw
-}:
-
-
-let meta = import ./meta.nix;
-in
-
-stdenv.mkDerivation {
-    name = "gromacs-4.5.5";
-
-    src = fetchurl {
-        url = "ftp://ftp.gromacs.org/pub/gromacs/gromacs-4.5.5.tar.gz";
-	md5 = "6a87e7cdfb25d81afa9fea073eb28468";
-    };
-
-    buildInputs = [cmake fftw];
-
-    cmakeFlags = ''
-      ${if singlePrec then "-DGMX_DOUBLE=OFF" else "-DGMX_DOUBLE=ON -DGMX_DEFAULT_SUFFIX=OFF"}
-    '';
-
-    inherit meta;
-}

pkgs/applications/science/molecular-dynamics/gromacs/default.nix

@@ -1,2 +1,49 @@
 
-import ./4.5.5.nix
+{ stdenv, fetchurl, cmake,
+  singlePrec ? true,
+  fftw
+}:
+
+
+let meta = import ./meta.nix;
+in
+
+stdenv.mkDerivation {
+  name = "gromacs-4.5.5";
+
+  src = fetchurl {
+    url = "ftp://ftp.gromacs.org/pub/gromacs/gromacs-4.5.5.tar.gz";
+    md5 = "6a87e7cdfb25d81afa9fea073eb28468";
+  };
+
+  buildInputs = [cmake fftw];
+
+  cmakeFlags = ''
+    ${if singlePrec then "-DGMX_DOUBLE=OFF" else "-DGMX_DOUBLE=ON -DGMX_DEFAULT_SUFFIX=OFF"}
+  '';
+
+  meta = {
+    homepage    = "http://www.gromacs.org";
+    licence     = "GPLv2";
+    description = "The GROMACS molecular dynamics software package";
+    longDescription = ''
+      GROMACS is a versatile package to perform molecular dynamics,
+      i.e. simulate the Newtonian equations of motion for systems
+      with hundreds to millions of particles.
+
+      It is primarily designed for biochemical molecules like
+      proteins, lipids and nucleic acids that have a lot of
+      complicated bonded interactions, but since GROMACS is
+      extremely fast at calculating the nonbonded interactions (that
+      usually dominate simulations) many groups are also using it
+      for research on non-biological systems, e.g. polymers.
+
+      GROMACS supports all the usual algorithms you expect from a
+      modern molecular dynamics implementation, (check the online
+      reference or manual for details), but there are also quite a
+      few features that make it stand out from the competition.
+
+	See: http://www.gromacs.org/About_Gromacs for details.
+    '';
+  };
+}

pkgs/applications/science/molecular-dynamics/gromacs/meta.nix

@@ -1,27 +0,0 @@
-
-
-
-meta = {
-  homepage    = "www.gromacs.org";
-  licence     = "GPLv2";
-  description = "The GROMACS molecular dynamics software package";
-  longDescription = ''
-    GROMACS is a versatile package to perform molecular dynamics,
-    i.e. simulate the Newtonian equations of motion for systems
-    with hundreds to millions of particles.
-
-	It is primarily designed for biochemical molecules like
-	proteins, lipids and nucleic acids that have a lot of
-	complicated bonded interactions, but since GROMACS is
-	extremely fast at calculating the nonbonded interactions (that
-	usually dominate simulations) many groups are also using it
-	for research on non-biological systems, e.g. polymers.
-
-	GROMACS supports all the usual algorithms you expect from a
-	modern molecular dynamics implementation, (check the online
-	reference or manual for details), but there are also quite a
-	few features that make it stand out from the competition.
-
-	See: www.gromacs.org/About_Gromacs
-  '';
-};

pkgs/top-level/all-packages.nix

@@ -8668,11 +8668,11 @@ let
     cmake = cmakeCurses;
   };
 
-  gromacsDouble = callPackage ../applications/science/molecular-dynamics/gromacs {
+  gromacsDouble = lowPrio (callPackage ../applications/science/molecular-dynamics/gromacs {
     singlePrec = false;
     fftw = fftw;
     cmake = cmakeCurses;
-  };
+  });
 
   ### SCIENCE/LOGIC