sortOn for older base package.

1 files changed, 6 insertions, 0 deletions

diff --git a/kiki.hs b/kiki.hs
index e06fa79..0284ff9 100644
--- a/kiki.hs
+++ b/kiki.hs
@@ -68,6 +68,12 @@ import qualified DNSKey as DNS
 import Data.Time.Clock.POSIX ( posixSecondsToUTCTime )
 import Debug.Trace
 
+#if !MIN_VERSION_base(4,8,0)
+sortOn :: Ord b => (a -> b) -> [a] -> [a]
+sortOn f =
+    map snd . sortBy (comparing fst) . map (\x -> let y = f x in y `seq` (y, x))
+#endif
+
 -- {-# ANN module ("HLint: ignore Eta reduce"::String) #-}
 -- {-# ANN module ("HLint: ignore Use camelCase"::String) #-}