Merge pull request #24922 from phunehehe/haskell-shell-hook

haskell-modules: fix shell hook

pkgs/development/haskell-modules/generic-builder.nix

···
         export NIX_${ghcCommandCaps}="${ghcEnv}/bin/${ghcCommand}"
         export NIX_${ghcCommandCaps}PKG="${ghcEnv}/bin/${ghcCommand}-pkg"
         export NIX_${ghcCommandCaps}_DOCDIR="${ghcEnv}/share/doc/ghc/html"
-        '' + (if isHaLVM
-	       then ''export NIX_${ghcCommandCaps}_LIBDIR="${ghcEnv}/lib/HaLVM-${ghc.version}"''
-	       else ''export NIX_${ghcCommandCaps}_LIBDIR="${ghcEnv}/lib/${ghcCommand}-${ghc.version}"'') + "${shellHook}";
+        ${if isHaLVM
+            then ''export NIX_${ghcCommandCaps}_LIBDIR="${ghcEnv}/lib/HaLVM-${ghc.version}"''
+            else ''export NIX_${ghcCommandCaps}_LIBDIR="${ghcEnv}/lib/${ghcCommand}-${ghc.version}"''}
+        ${shellHook}
+      '';
     };
   };