Fix backwards-compatibility

Author: Lennart Spitzner

cabal-install/Distribution/Client/Status.hs

@@ -85,6 +85,7 @@ import System.FilePath                        ( splitFileName
                                               , joinPath
                                               , takeDirectory
                                               )
+import Data.Functor                           ( (<$) )
 import Control.Monad                          ( when
                                               , forM
                                               , guard
@@ -94,8 +95,10 @@ import Data.Version                           ( showVersion
                                               )
 import Data.Maybe                             ( isJust
                                               )
-import Data.List                              ( sortOn
-                                              , groupBy
+import Data.List                              ( groupBy
+                                              , sortBy
+                                              )
+import Data.Ord                               ( comparing
                                               )
 import Text.PrettyPrint                       ( empty
                                               , ($$)
@@ -106,7 +109,9 @@ import Text.PrettyPrint                       ( empty
                                               , ($+$)
                                               , (<+>)
                                               )
-import Data.Monoid                            ( (<>) )
+import Data.Monoid                            ( (<>)
+                                              , mappend
+                                              )
 import Data.List                              ( inits )
 import Data.Foldable                          ( asum )
 
@@ -307,7 +312,9 @@ status verbosity globalFlags statusFlags = do
     installedPackageIndex <- getInstalledPackages verbosity comp dbs conf
     let pkgs = allPackages installedPackageIndex
         pkgTuples = [ (root, disp $ sourcePackageId pkg) | pkg <- pkgs, root <- [x | Just x <- [pkgRoot pkg]]]
-        grouped = groupBy (\a b -> fst a == fst b) $ sortOn fst pkgTuples
+        grouped = groupBy (\a b -> fst a == fst b)
+                $ sortBy (comparing fst)
+                $ pkgTuples
         groups = [(fst (head x), map snd x) | x <- grouped]
     let packageDoc ps = if    Cabal.fromFlag (statusPackages statusFlags)
                            || Cabal.fromFlag (statusAll statusFlags)