Define Semigroup instances for base>=4.9

See ekmett/semigroups#56 for more details

Author: hvr

Data/IntMap/Base.hs

@@ -222,6 +222,9 @@ import Data.Monoid (Monoid(..))
 import Data.Traversable (Traversable(traverse))
 import Data.Word (Word)
 #endif
+#if MIN_VERSION_base(4,9,0)
+import Data.Semigroup (Semigroup((<>), stimes), stimesIdempotentMonoid)
+#endif
 
 import Control.DeepSeq (NFData(rnf))
 import Control.Monad (liftM)
@@ -305,8 +308,16 @@ infixl 9 \\{-This comment teaches CPP correct behaviour -}
 
 instance Monoid (IntMap a) where
     mempty  = empty
-    mappend = union
     mconcat = unions
+#if !(MIN_VERSION_base(4,9,0))
+    mappend = union
+#else
+    mappend = (<>)
+
+instance Semigroup (IntMap a) where
+    (<>)    = union
+    stimes  = stimesIdempotentMonoid
+#endif
 
 instance Foldable.Foldable IntMap where
   fold = go

Data/IntSet/Base.hs

@@ -173,6 +173,9 @@ import Data.Maybe (fromMaybe)
 import Data.Monoid (Monoid(..))
 import Data.Word (Word)
 #endif
+#if MIN_VERSION_base(4,9,0)
+import Data.Semigroup (Semigroup((<>), stimes), stimesIdempotentMonoid)
+#endif
 import Data.Typeable
 import Prelude hiding (filter, foldr, foldl, null, map)
 
@@ -247,8 +250,16 @@ type Key    = Int
 
 instance Monoid IntSet where
     mempty  = empty
-    mappend = union
     mconcat = unions
+#if !(MIN_VERSION_base(4,9,0))
+    mappend = union
+#else
+    mappend = (<>)
+
+instance Semigroup IntSet where
+    (<>)    = union
+    stimes  = stimesIdempotentMonoid
+#endif
 
 #if __GLASGOW_HASKELL__
 

Data/Map/Base.hs

@@ -275,6 +275,9 @@ import Control.Applicative (Applicative(..), (<$>))
 import Data.Monoid (Monoid(..))
 import Data.Traversable (Traversable(traverse))
 #endif
+#if MIN_VERSION_base(4,9,0)
+import Data.Semigroup (Semigroup((<>), stimes), stimesIdempotentMonoid)
+#endif
 
 import Control.DeepSeq (NFData(rnf))
 import Data.Bits (shiftL, shiftR)
@@ -340,8 +343,16 @@ type role Map nominal representational
 
 instance (Ord k) => Monoid (Map k v) where
     mempty  = empty
-    mappend = union
     mconcat = unions
+#if !(MIN_VERSION_base(4,9,0))
+    mappend = union
+#else
+    mappend = (<>)
+
+instance (Ord k) => Semigroup (Map k v) where
+    (<>)    = union
+    stimes  = stimesIdempotentMonoid
+#endif
 
 #if __GLASGOW_HASKELL__
 

Data/Sequence.hs

@@ -175,6 +175,9 @@ import Data.Foldable (Foldable(foldl, foldl1, foldr, foldr1, foldMap), foldl', t
 #if MIN_VERSION_base(4,8,0)
 import Data.Foldable (foldr')
 #endif
+#if MIN_VERSION_base(4,9,0)
+import Data.Semigroup (Semigroup((<>)))
+#endif
 import Data.Traversable
 import Data.Typeable
 
@@ -543,7 +546,14 @@ instance Read a => Read (Seq a) where
 
 instance Monoid (Seq a) where
     mempty = empty
+#if !(MIN_VERSION_base(4,9,0))
     mappend = (><)
+#else
+    mappend = (<>)
+
+instance Semigroup (Seq a) where
+    (<>)    = (><)
+#endif
 
 INSTANCE_TYPEABLE1(Seq,seqTc,"Seq")
 

Data/Set/Base.hs

@@ -199,6 +199,9 @@ import Data.Bits (shiftL, shiftR)
 #if !MIN_VERSION_base(4,8,0)
 import Data.Monoid (Monoid(..))
 #endif
+#if MIN_VERSION_base(4,9,0)
+import Data.Semigroup (Semigroup((<>), stimes), stimesIdempotentMonoid)
+#endif
 import qualified Data.Foldable as Foldable
 import Data.Typeable
 import Control.DeepSeq (NFData(rnf))
@@ -245,8 +248,17 @@ type role Set nominal
 
 instance Ord a => Monoid (Set a) where
     mempty  = empty
-    mappend = union
     mconcat = unions
+#if !(MIN_VERSION_base(4,9,0))
+    mappend = union
+#else
+    mappend = (<>)
+
+instance Ord a => Semigroup (Set a) where
+    (<>)    = union
+    stimes  = stimesIdempotentMonoid
+#endif
+
 
 instance Foldable.Foldable Set where
     fold = go