Merge branch 'master' into dev-metadata-route

Conflicts:
	tests/Hakyll/Core/Rules/Tests.hs

1 files changed, 8 insertions, 16 deletions

diff --git a/src/Hakyll/Core/Rules/Internal.hs b/src/Hakyll/Core/Rules/Internal.hs
index 09d9b1e..6bb82df 100644
--- a/src/Hakyll/Core/Rules/Internal.hs
+++ b/src/Hakyll/Core/Rules/Internal.hs
@@ -16,9 +16,9 @@ import           Control.Applicative            (Applicative, (<$>))
 import           Control.Monad.Reader           (ask)
 import           Control.Monad.RWS              (RWST, runRWST)
 import           Control.Monad.Trans            (liftIO)
+import qualified Data.Map                       as M
 import           Data.Monoid                    (Monoid, mappend, mempty)
 import           Data.Set                       (Set)
-import qualified Data.Set                       as S
 
 
 --------------------------------------------------------------------------------
@@ -92,25 +92,17 @@ instance MonadMetadata Rules where
 runRules :: Rules a -> Provider -> IO RuleSet
 runRules rules provider = do
     (_, _, ruleSet) <- runRWST (unRules rules) env emptyRulesState
-    case findDuplicate (map fst $ rulesCompilers ruleSet) of
-        Nothing  -> return ruleSet
-        Just id' -> error $
-            "Hakyll.Core.Rules.Internal: two different rules for " ++
-            show id' ++ " exist, bailing out"
 
+    -- Ensure compiler uniqueness
+    let ruleSet' = ruleSet
+            { rulesCompilers = M.toList $
+                M.fromListWith (flip const) (rulesCompilers ruleSet)
+            }
+
+    return ruleSet'
   where
     env = RulesRead
         { rulesProvider = provider
         , rulesMatches  = []
         , rulesVersion  = Nothing
         }
-
-
---------------------------------------------------------------------------------
-findDuplicate :: Ord a => [a] -> Maybe a
-findDuplicate = go S.empty
-  where
-    go _ []              = Nothing
-    go s (x : xs)
-        | x `S.member` s = Just x
-        | otherwise      = go (S.insert x s) xs